What are the pink and purple lines in InDesign?

Answer 1

These are guide lines that allow you to align different elements in the document you're creating. The default for them is set to "snap to", meaning that if you pull a photo, or block of text toward the guideline, it will snap into place at the spot the software believes you want it. If you don't want the guides, just right click on one of them, and select "Clear Guides".