Question Daughter board connectors

[PaulDesmond]

I need more daughter board connectors. I have an Asus M5A78L-M-USB3. It has an PCI Express x1 socket. What is the point of this connector. Nothing fits it. I wanted to get a 1Gb network card but no available slots.
I have looked at a more modern motherboard GA-970A-DS3P (DDR4). This has 3 of these ports. What is the point of it all and how does this help me with a fast network conector.

 

[CountMike]

Many adapters are made for PCIe x1 whose speed is enough for less demanding tasks, modems, WiFi cards, serial or parallel ports, even some audio cards.
https://www.amazon.com/Network-Card..._feature_keywords_three_browse-bin:6011949011

https://www.amazon.com/TP-Link-TG-3468-Gigabit-Ethernet-PCI-Express/dp/B003CFATNI

https://www.amazon.co.uk/Internal-S...31,p_n_feature_keywords_browse-bin:1032504031

Just few examples. BTW. PCIe x1 cards also work in x4, x8 and x16 slots.