Help with understanding GPM data : meteorology

I’m new to programming and am using R to create a simple dataset combing lat lon time and precipitation values to evaluate.

I downloaded IMERG data using Giovanni and used R to read the data using nc_open. my next step is to get variables. I’m able to get lat lon values, however, I’m unable to see the time variable or the precipitation values.

Am I missing something basic or have downloaded the wrong dataset?