“It only takes me about 15 minutes.”
You're out to lunch with a group of coworkers and talking about your daily routines. One coworker says that her commute to work is 45 minutes long. You want to continue the conversation, so you tell her this about how long your commute time is.
It only takes me about 15 minutes.
This is a phrase for saying how long a common process or action is.
It often expresses how long a person's travel time is:
It takes me 20 minutes to get to work.
It can also be used to talk about other actions, like taking a shower, getting dressed, and putting on makeup to get ready to go out:
It takes Erin an hour and a half to get ready.
And you can use it to talk about natural processes:
It takes about two weeks for the fruit to ripen.
In this case, "only" is used because 15 minutes is not a long time compared to most people's commuting time.