という is a versatile particle-like expression that links two parts of a sentence. Its most common use is to define or name something: you put the name or definition before という, and then the thing it applies to after. For example, これは「さくら」という花です means 'This is a flower called sakura'. You can also use it to quote what someone said or thought: 彼は行くと言いました means 'He said he will go'. The quoted content must be in plain form before という.

When attached to a noun, という can also mean 'that is called' or 'named', and it often appears in phrases like 〜という人 (a person named...), 〜という町 (a town called...). In more advanced usage, it can add emphasis or explanation, but at N4 level, focus on naming and quoting.

Note that という has another totally different meaning: when repeated as という〜という〜 or used with counters, it can mean 'every single' with no exceptions, but that is a separate grammar point. Here we only cover the 'called/named/that' usage.