The deep, warm voice of a cello is traditionally linked to melancholy and depth of feeling. Playing it in a dream is read as embracing an emotion rather than holding it at arm’s length.
Where in your waking life have you met something like this lately?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.