1. en los países hispanos los hombres y las mujeres
besan cuando
conocen. en los estados unidos generalmente
damos la mano cuando
conocemos.

En los países hispanos los hombres y mujeres se besan cuando se conocen. En los Estados Unidos generalmente nos damos la mano cuando nos conocemos.

Explanation:

In the first sentence there must be added "se" before besan. It means we're talking about other people. In this case, Hispanic people.

In the second sentence, there must be added "nos" before besamos. It means we're talking about us. In this case us is Americans.

Both "se" and "nos" are what's called in Spanish "pronombres reflexivos", that is to say, reflexive pronouns in English. They're used in verbs which need to refer to a subject. In this case, the verb "besar" (kiss) must be accompanied by the person or the people do the action in order to make sense.