So i know brute force means like you try all the combinations..
1. But its a computer entering each one etc over and over right? And not like a person doing it manually right? Now with brute force, is it a program that does it or is it a computer?

Theoretically, both is called bruteforcing.
But if you'd want to try to bruteforce a mnemonic (or a password or whatever), i'd recommend you use a computer for that.
~snip~
Your 12 word mnemonic is secure.
4-5 words can be bruteforced quite easily currently. But you shouldn't think about it, since you shouldn't expose any words of your mnemonic at all.
Better keep it completely secure than to think about how many words you could expose and still be safe.
Well if you do it manually, you are basically typing it yourself which is time consuming... but when a computer does it... can someone explain how that works? So you would see on the screen... it typing those word combinations and pressing enter each time... then move on to the next word etc? You can do this with a computer you have or you need to buy special equipment for it?