The answer depends completely on the design of the individual device.
I understand in England you use power at 220 VAC, 50 or 60 Hz, and common electrical cords have, on their "wall" end, 2 prongs. (I could be wrong on the prongs). Throughout the USA and Canada the common power system offers at a wall outlet 120 VAC at 60 Hz, and the standard plug on the cord end has three prongs. Common circuits in a home are limited (by fuse or breaker) to 15 amps, but some may have 20 amp breakers and wiring. There are special different cords, plugs and outlets for high-power devices using 120 VAC at higher currents or 240 VAC (like stoves and clothes dryers) in the home.
If you look at a North American wall outlet as commonly installed, it has a pair of outlets mounted vertically as one unit. On each there are three openings for prongs from the plug. The two upper ones are in a straight horizontal line and are vertically-oriented straight slots. The third hole is below the other two, centred between, and round. The upper LEFT slot is larger (taller) than the upper RIGHT slot.
The supply to a house uses what is called a Grounded Neutral 120 / 240 VAC system. Three wires come into the house from the transformer outside. Two of these are called Hot or Lines, and the third is called the Neutral Line; short-form labels are L1 and L2 and N. Think of them this way: the L1 and L2 wires come from the two ends of a transformer winding, and the N line comes from a centre connection of that winding. The result is that there is a 240 VAC potential between L1 and L2, but there is 120 VAC available between L1 and N, and again between L2 and N. At the transformer, and again at the breaker box inside the house where the power enters, the N line is connected to a solid true earth Ground so that IN THE BREAKER BOX it is at zero volts at all times with respect to true Ground. However, the in-house power cabling also has a separate Ground bus connected to the same true earth Ground. The difference inside the house distribution circuits is this: current from the source on either the L1 or L2 lines goes out to several outlets in the house and through devices in use, and returns via the N lines. So the N lines carry significant currents and hence, because of minor non-zero wire resistance, may NOT be at zero volts at any given spot. However, the separate Ground wires also in the distribution cabling should never have any current flowing in them except in unusual temporary circumstances, and hence can be reliably used as true Ground connections. These true Grounds are the wires connected to the round third hole in the wall outlet. They are used as a safety measure and can also function as a good Ground for reducing low-voltage induced electrical noise.
Many devices, of course, have power cords that are permanently wired into the interior components. However, a lot of electronic devices like computers have detachable cords. For these latter it often happens that you can buy replacement cords such that one end matches the socket on the back of your device, and the other has a common North American style 3-prong plug. That is what you are looking for, OP.
HOWEVER, whether that can work does depend on how the device was designed. There are three main groups here:
1. A device that is clearly designed only to work on one power system, such as something labelled for 220 VAC, 50 or 60 Hz; you cannot simply replace the cord on such a device - it will not work at half the supply voltage it was designed for. A 220 VAC electric teakettle would never boil water when plugged into a 120 VAC supply.
2. Devices designed to work with either 120 VAC or 240 VAC, and including a manual switch (often recessed to avoid changing it by accident); for these you can change the power cord AND change the manual setting of voltage being used. There may be a slight mismatch of frequency, but for most devices (a cell phone charger or a computer PSU, for example) a difference of 50 Hz or 60 Hz will not matter much. For some things like AC motors in a dual-voltage hand-held hair dryer gun it may mean they will run at a slightly different speed. For some things like a dual-voltage hair curling iron it won't matter at all.
3. Devices designed to work over a wide range of supply voltages - for example from 90 to 250 VAC - such as many types of computer PSU modules; these normally have no manual switch to set because they adjust themselves to whatever supply is provided within that range, and you do NOT need to make any adjustment beyond changing the cord. You MAY also have an option simply to replace the plug on the cord end IF the cord has the correct number and size of conductors and IF you make the connections properly.