Look after - means to take care of someone or something. For example, "I need to look after my little brother while my parents are out."
Look up - means to search for information in a reference book or online. For example, "I will look up the definition of that word in the dictionary."
Look forward to - means to be excited and anticipating something in the future. For example, "I am looking forward to my vacation next month."
Look for - means to search for something or someone. For example, "I am looking for my keys, have you seen them anywhere?"
Look after your health by eating well, exercising regularly, and getting enough sleep.
I need to look up the address of the restaurant before we leave.
I am really looking forward to the concert next week.
I am looking for a new book to read, do you have any recommendations?