You have a rep power of two, it looks like (you can see that under your username) it is like giving a "like" to someone, but usually people give it when they
really like something, or feel like it's an insightful post or just feel like the person is on a good track and deserves "reputation".
You can check the reputation you've gotten by clicking on "settings" this will allow you to see how much reputation you've gotten, and sometimes their comment on who they are and why they gave it.
You give reputation by clicking on the little star of David at the bottom of the post you want to give a rep to
(Don't click on the triangle with the ! in it, that will report the post
).