Romeo uses a metaphor when he says: “You bad'st me bury love.”
A metaphor is a comparison using a verb, when you say that something is something. It is a type of figurative language used to describe something not literally.
Romeo says this in a conversation with Friar Lawrence. Romeo comes to Friar Lawrence and tells him that he is in love with Juliet and wants to marry. Friar Lawrence is, understandably, surprised. After all, it was not long ago that Friar Lawrence was consoling Romeo crying for Rosaline. He reminds him of this.
Holy Saint Francis! What a change is here!
Is Rosaline, that thou didst love so dear,
So soon forsaken? Young men's love then lies
Not truly in their hearts, but in their eyes. (Act 2, Scene 3)
Basically, he is telling Romeo that young men fall in love with beauty, not with personality. He thinks that Romeo’s love for Juliet is lust, and only skin-deep.
Romeo objects. He says that Friar Lawrence would often scold him for loving Rosaline (Friar Lawrence tells him it was “doting” and not loving). This is when Romeo makes the above comment about burying his love. Basically, he is saying that Friar Lawrence asked him to stop loving Rosaline. He did! Now he loves Juliet. Friar Lawrence has a witty comeback in a metaphor of his own.
Not in a grave
To lay one in, another out to have. (Act 2, Scene 3)
In other words, young lad, I did not tell you to stop loving one girl in order to instantly fall for another. He took one girl out of the grave (Rosaline) and put another in (Juliet).
Romeo assures Friar Lawrence that his love is genuine. Ultimately, Lawrence agrees because he is interested in bringing the two families together and ending the feud. It will be their doom, because although his heart is in the right place, it is his intervention that causes the tragedy because he marries them in secret first, and then secretly helps Juliet second. Maybe Romeo should have taken his advice.