Can anyone explain witnessing please?

I created this account years ago. Barely knew what I was doing then. Now I know even less and it seems more confusing. There seems to be a lot of tech talk, and very little plain talk. I was prompted to vote for witnesses when I logged in so I did. I searched this site for "witness" but didn't seem to find anything that helped. So I just randomly voted for the first 30 since I had 30 votes and there were only 50 to choose from but I have no idea how that helps, what it does for people that have a witness node, and whether or not it did anything for me.

I connected a new Tron wallet too since I was also prompted to do that but nothing seems to be happening there after I imported my private key, maybe my power is too low? It mentioned SR but without defining what SR actually is.