How to find out what is trying to install on my phone

My husband’s Moto G1 has a triangle message “Restart your phone. Please restart to complete installation.” How do we find out what it is trying to install?

The System page says the Android version is 5.1 and the Android security patch level is 2016-08-01.

I have the same message on my phone this morning 5/25/2020. What’s up?
Android version 5.1 security patch level 2016-02-01

Message an
Expert customer