How does a hacker get apps ointo your phone?

I have noticed an app on my phone that I don't recall installing.

I am concerned that a hacker may have done this. I am pretty sure no one has had physical possession of the phone so I am wondering how this could be done remotely?

I have run a Malwarebytes Premium scan and it showed up no malware infections. There also appears to be some native Android Software scans for threats and it reported no infections as well.