Questions & Answers about Я жду друга на перекрёстке.
Because друг is the direct object of жду, so it must be in the accusative case.
- Nominative (dictionary form): друг – "friend" (subject)
- Accusative (masculine animate): друга – "friend" (object, a person)
For masculine animate nouns, the accusative form looks like the genitive. So я жду друга literally is "I am-waiting friend-ACC" = "I am waiting for (a/the) friend."
In Russian, ждать already means "to wait for". It takes a direct object in the accusative case and does not use a preposition:
- ждать друга – to wait for a friend
- ждать автобус – to wait for the bus
If you tried to add a preposition like для or за, it would be wrong in this meaning. So я жду друга fully covers "I’m waiting for a friend."