who said it and what does it mean

Romeo says this to Juliet. In context, he's telling her that although he isn't a pilot (navigator), he would sail around the world for her.

Here Romeo unintentionally reiterates his earlier assertion that fate is his true pilot:

He that hath the steerage of my course

Direct my sail! (1.4.112-13)

Note how Romeo uses the same motif at the sorrowful end of the lovers' journey, apostrophizing the poison itself as his final pilot:

Thou bitter pilot, now at once run on

The dashing rocks thy seasick weary bark! (5.3.117-18)