Grid system on games possible?

I was thinking about it recently as a mechanic for my future game. It's an RPG, so expect it to be similar to final fantasy tactics or something

I'm not requesting or anything, I'm just asking on how this would be possible and worked out.

So, here are some questions:

I assume that, let's say, 8 x 8 grid, I have to name them like 1A for the first tile, 2A, second... etc.

Second, I have some question about ... okay. FOR example, when a player presses a letter, let's say "y" on that tile (let's say 2B) , the tile would turn green and the tile's beside it(1 tile radius), how can this be done? Would the tile always check if the "y" will be affected? And this has to apply on any tile too.

I'm just thinking that if I use a system like this, I have to keep putting conditions on every tile, and it keeps repetitive, so is there any shortcut to this? I'll make some scripts soon about this, after my exams.