The engine lines have an evaluation number. If you have a bunch around the same evaluation, then more lines are better in the sense you can explore more options. If you have only one line that shows a good result for that sides move, then it doesn't matter what the other lines say. For example, a mate in 3 is a mate regardless what it says for other lines.
Earlier in the game, the engine lines don't matter as much, but you still want to keep track when deciding what you want to play in the beginning.
HI im new to chess engines. Im wondering what are "Lines" in the chess engine display. I am useing chessx gui. Are they different ways the game can go and the engine is finding the best move? Are more lines better ?