* "Tu amistad": This means "your friendship".
* "el mejor": This means "the best".
The phrase is missing a verb. It's like saying "your friendship the best" in English, which doesn't make sense.
Here are some ways you could phrase it correctly in Spanish:
* "Tu amistad es la mejor": This means "Your friendship is the best."
* "Eres el mejor amigo": This means "You are the best friend."
* "Tu amistad es lo mejor": This means "Your friendship is the best thing."
It depends on the context and what you're trying to say!