Get the gist of something

The phrase "get the gist of something" means to understand the main idea or general concept of a topic, without necessarily knowing all the details or nuances. It refers to grasping the essential or core meaning of a message, conversation, or piece of information.

For example:

Even though the lecture was complex, most students were able to get the gist of the professor's explanation.

After skimming the article, she felt that she had gotten the gist of the author's argument.

While I didn't catch every word, I got the gist of what he was trying to say.