The phrase "to tie up" means to bind or secure something using a rope, cord, or other binding material. It can also mean to occupy someone's time or attention with something else, often in a negative way. For example, if you have a lot of errands to run and need to leave the house, you might say "I have to tie up some loose ends before I go." This means that there are still things left undone that need to be taken care of before you can leave.