Friends are special contacts. Unlike a normal contact, a friendship is based on reciprocity. You can receive friendship offers and offer friendships yourself. Each member who receives a friendship offer can then decide whether to accept the offer or not.
The more friends you have, the better your chances of meeting other members through them. Because with all your friends you appear in their friend list and are thus visible for all visitors.
In order to offer friendship to a member, you must first save the member as a contact. Then you open the profile of the member in question and open the context menu (via the three dots) in the top right corner.
Then you have the "Edit contact" function. If you click on it, you can offer a friendship. If the other person accepts the friendship, you will receive a message.