Output file when training detectnet 2

After training this file gets saved into the respective directory:

events.out.tfevents.1589478961.19dc1442f01d

What events does this folder contain and how can I extract the information from it?

This event file records some summary data.
Reference: https://github.com/tensorflow/tensorboard/blob/master/README.md

But unfortunately, currently tlt docker do not support tensorboard for visualization.

Can I use that file and use it with tensorboard outside of tlt and do it my own?

Yes, you could do so. However, this only shows cost plots.