To understand what someone is saying, to follow something someone said, or a concept that is being put forth. Similar words include gleaned and gleaning.
I glean that 2+2=4
I can't glean a single thing that moron was saying.
To show a grasp or, comprehension, of a subject matter, material, or, functionality, with limited information, or time to fully understand or totally absorb, what it is we're seeing or doing.
Can be an intuitive first impression of a person place or thing