This structure use the te form with the verb “to put” to express that you will perform an action and then leave it in that state (typically in preparation for something in the future). For example, you might have guests coming in a few hours so you say to your partner, “I’ll put the wine in the fridge” or you might be late for a meeting so you give someone a call to let them know in advance. It doesn’t always have a direct equivalent in English.
|It looks like we’re going to be late so I’ll give James a call.|
|To cool the beers.|
|The clients are coming around 3 o’clock so let’s book a meeting room.|
|Keep a spare battery.|
In casual conversation, the ～ておく sometimes gets abbreviated to 〜とく.
|It’s a good job I bought it [because the price has now gone up].|