What is the meaning of hang on?

verb

• Fix to; attach.
  • usage: "append a charm to the necklace"
  • synonyms: append, tag on, tack on, tack
• Be persistent, refuse to stop.
  • usage: "he persisted to call me every night"; "The child persisted and kept asking questions"
  • synonyms: persevere, persist, hang in, hold on
• Hold the phone line open.
  • usage: "Please hang on while I get your folder"
  • synonyms: hold the line, hold on