Welcome to Tom's Hardware, @gotamaone!
The SATA connectivity is backward compatible. This basically allows you to use SATA III SSD on a SATA II motherboard. However, when it comes to the transfer rate and performance of solid-state drives they are capable of reaching up to ~550 MB/s, which will be bottlenecked by the SATA II port on your laptop that is capable of transferring only at ~ 300 MB/s ( SATA II = 3 Gb/s = 300 MB/s).
Yet again, the difference of booting from an SSD will still be noticeable even though you won't be reaching its full speed potential. So yes, it will still be faster than a regular 2.5" mechanical hard drive.
Hope I was helpful. Let me know if you have more questions!
SuperSoph_WD