It depends, most casinos won’t allow you to use more than one bonus at once, but many will offer multiple bonuses that you can take advantage of one after another.
A good example of this is how some casinos will offer welcome packages which include bonuses over multiple deposits, as much as your first four deposits at times! This is really beneficial for the player, as you can keep playing and keep receiving deposit rewards! Of course, this is in place to entice the player to spend more time on the casino’s website, but free stuff is always a plus! When attempting to take advantage of any bonus, it is always a great idea to read the terms and conditions, as these will usually explicitly state any limitations the bonuses might have, including whether you can use more than one at once.