This is of course the scene where Romeo famously tries to stab himself out of anguish because of what he has done in killing Tybalt and his subsequent banishment. In response to his attempt to stab himself, the Friar gives a long speech which both conveys his anger towards Romeo and his concern. Note how his anger is communicated at the beginning of his speech:
Hold thy desperate hand.
Art thou a man? Thy form cried out thou art;
Thy tears are womanish, thy wild acts denote
The unreasonable fury of a beast.
The Friar thus begins by attacking Romeo's manhood, suggesting he is not actually a man, as he is behaving like a woman with his tears but also like a "beast" in his wild actions. The Friar then goes on to point out all of the things that Romeo can be thankful for, refering to how they form "A pack of blessings light upon thy back." His care and concern for Romeo is shown in the way that he paints a picture of how this horrendous situation can be resolved. Talking of Mantua, where Romeo must stay in exile, the Friar says:
Where thou shalt live till we can find a time
To blaze your marriage reconcile your friends,
Beg pardon of the prince, and call thee back
With twenty hundred thousand times more joy
Than thou went'st forth in lamentation.
Thus in this speech Friar Lawrence shows both his anger at Romeo's attempt to kill himself and also his deep abiding love and concern in the way that he makes Romeo see that there is hope even in the most hopeless of situations.