Does the term line of dialogue mean literally one or a string dialogue?

"Line of dialogue" can refer to both a single line spoken by a character and a string of dialogue.

Single Line:

* Example: "The most common usage is to describe a single utterance, such as 'Hello, how are you?'"

String of Dialogue:

* Example: "The line of dialogue between the two characters builds tension and reveals their conflict." Here, it refers to a sequence of dialogue, maybe a conversation or an argument.

The context usually clarifies which meaning is intended.

It's best to consider the context when encountering "line of dialogue" to understand whether it refers to a single utterance or a string of dialogue.