What dose this saying really mean?

This saying is very relevant in politics. A well known and influential person especially should heed these words.

Someone like that must keep a close eye on their enemies so that they know their strengths and weaknesses, and where they are etc. When an enemy is far away, who knows what they are up to?

The way such a person could do that is to be on good terms with their enemies. Making friendly relations with them and keeping ties with them.

They would do things like give gifts and shake hands in public and find everything about the other person. They say nice things to them in front of their people and things like that..

It's just about politics. It's for kings, presidents, rulers, etc....

It means you should keep your friends close, but your enemies closer because if you keep your enemies closer, you gain their trust. Once you have done so, you can totally dump them and win the prize or whatever.

The saying is supposed to be for tournaments and stuff like that.

Its a better idea to keep a closer eye on your enemies rather than your friends. By keeping your enemies close, you know their moves, moods and characteristics, and you can even sometimes be undetected as their enemy.

If the shoe fits, wear it. That means if the situation someone is describing applies to you, then you should accept the challenge, or rise to the occasion. It also has a derogatory meaning, as, for example, if someone is talking about bad drivers, and you are one, you should accept what is being said.

Keep an eye on people that could turn on you

BTW-It's spelled does not dose.

enemies do more harm than friends

Friends are trusted, enemies are unpredictable and cause problems.

watch your back

knowing your enemies moves/ideas keeps you from them surprising you

Knowing your enemies inside out so you can exploit them?

you need to really watch what they are up to

who knows and who gives a flying fuc