What does it mean for girls to give this blessing to boys?

"Girls give boys this blessing" can refer to different things, depending on which "blessing" it refers to. If you mean the word "Fu", it is usually regarded as a symbol of good luck in China culture, representing happiness and good luck. Therefore, if a girl gives a boy a word "Fu", it may mean that she wishes him good luck and happiness.

On the other hand, if you mean other forms of "blessing", such as red envelopes or gifts, then their meanings may be related to specific cultures and traditions. In China culture, red symbolizes auspiciousness and good luck, so red envelopes and red gifts are usually regarded as auspicious gifts. If a girl gives a boy a red envelope or a red gift, it may mean that she wants him to be lucky and happy.

In short, the specific meaning of "girls give boys this blessing" depends on the form and cultural background of "blessing".