Keeps the beat and tells you to ramp up, ramp down (volume ) and when to stop or start. He points the stick at your instrument group, makes eye contact, to let you know.

I was only in band (we had band not orchestra) in 5-8th grade.

But I'll tell you, it's very intuitive. I never was like "what's he mean?".

It's just like very obvious what the conductor* is indicating to you.