to understand; to know; to comprehend

She plays piano as well as the guitar.

The more difficult the questions are, the less likely I'll be able to answer them.

Gorillas cannot use their lips and tongues to speak, but they can communicate with people in other ways.

Noise pollution could be avoided if only people were more sensitive to the environment.

It warms your heart when, while listening to a song in a (seemingly!) foreign language — Slovak, Macedonian, or Slovenian — you hear words that you have known since your childhood and even understand whole phrases.