It may not help you tie your shoe but that little plastic tip keeps the rest of the shoelace, the shoe string from unraveling into weak and useless threads.
它可能不能帮你系鞋带，但那小小的塑料头可以让鞋带的其余部分不会散开成脆弱无用的线。
2
He bent over to tie his shoe.
他俯身系鞋带。
《新英汉大辞典》
3
Suppose you need to pause for some period of time, say to tie your shoe.