How do you make signs in The Sims 2?
 

I was wanting to know how to make signs for buisnesses like stuff that Architect of the Future does.

You would need to be a bit more specific.

You could create wallpaper murals that are signs. You could recolor an existing mesh (MogHughson has one) or find one via WCIF. You could create a new mesh.

Your in the right forum, now you just need to decide which route you would like to go and read some tutorials.

I really don't know all too much about making things like that I don't know how fimilar you are with Architect of the Future's work, if so , I want to make signs like he does, like the signs on the wall.

Start by making a table as advised in the start to finish tutorial (in the tutorials area in Object Meshing). Then open up the stuff you'd like to emulate and look how it's done. Once you know the basics, you'll probably be much better prepared to do what you want, and to understand how he's done his.

I was searching for how to make signs today, and then obviously I came across this thread. Ideally something like the signs in Minecraft would be what I need. I would like to choose a blank sign, then place it. Afterwards, a dialog would pop up in which I would type the text that I want on the sign. After I close the dialog, the sign would be permanently populated with that text. Is that functionality even possible?

No, I'm afraid not. TS2 doesn't have that kind of text rendering ability. You could, however, have a sign which allows you to pick from a set of predefined texts.