apollocrush, this could be a very long explanation. Make it short. Center is making noise as is the quarterback. Counts and plays along with blocking assignments could for example use colors, states or any combination of calls. For example . . . center says a number of things calls the color green, immediately after the green comes the blocking assignment for #29.
Quarterback can change that call if #29 shifts prior to snap, quarterback calls a series and the scheme can be after the color red or whatever. There are keys prior to snap, thus causing some "newbies" to miss assignments. Manning has become a master at this. Hope this helps, probably not. Will get easier your sophomore year. Just teasing . . .