but in the objective based things will I be playing against real players or bots?
You can play solo with and against bots.
Or coop with friends (and bots) against bots.
Or online with (or without) friends and players and bots against players and bots.
The bots work a little different in BRINK than they do in other games.
If they are not disabled, they will always fill up the teams so it's
always 8v8. However, a player can join (if you're playing online) at any given time and will simply replace a bot. The same goes for when a player leaves. A bot will take his place.