The bet/call is when we bet with the intention of calling our opponent's raise. The bet/call can be done for several reasons. First, against a very aggressive player who bluffs very often, a bet/3bet rather than a bet/call may cause him to call his bluff and fold. You don't want that. Also, simply calling his bet will hide the strength of your hand. We can also bet/call because our hand is not strong enough for bet/3bet, but too strong for bet/fold. Let's imagine a color draw with overcards for example.
Precise situations of bet/call
As mentioned in the paragraph above, the situations of 10 can be numerous. Let's say you have a pair of 9s in your hand on a 5 7-8-9 all heart. You bet and your opponent (a very conservative player who is known for his passivity) raises your bet to flop. Here you are often against straights or colours (flushs). You could also be against a three of king of 7 or 8. The bet/3bet option would accomplish nothing since by raising your raise, you would be putting down the weakest part of your opponent's hand rank by having action against his hands that dominate you. The bet/call option would therefore be the obvious choice.