What do these 2 functions do?

Hello, Tom!

Thank you for posting your question!

Are you referring to Dimensions option of slider text layers? If so, please note, that Dimensions setting lets you set the size of the text layer. Whereas Break-word setting configures how the text is going to be wrapped.

In case this option is enabled, the words in the text will be cut when wrapping the text to the next line.

Let me know in case you have further questions.
Thanks! Have a great day!