Learn Hardcore Russian: У входа в театр мы ждём друзей. - At the entrance to the theater, we are waiting for friends.

У + Genitive commonly means by/at/near something (a location next to a reference point).
So у входа literally means by the entrance / at the entrance (not “inside” the entrance).

Why is it у входа (not у вход)? What case is входа?

After у, Russian uses the genitive case.
вход (nominative) → входа (genitive singular).
So: у + Gen. → у входа.

Why is it в театр (not в театре) in входа в театр?

Because вход в театр is a fixed-type construction meaning “an entrance into/to the theatre” (direction “into”), so it uses в + accusative:

театр (accusative singular) = театр (same form as nominative for this noun)

If you meant location “in the theatre,” you’d use в театре (prepositional):

в театре = “in the theatre”

But here it’s “the entrance (that leads) into the theatre,” not “the entrance located in the theatre.”

What is the structure of у входа в театр—is в театр describing where we wait?

Grammatically, в театр attaches to вход:

вход в театр = “the entrance to/into the theatre”
Then the whole phrase becomes:
у [входа в театр] = “by [the entrance to the theatre]”

So it’s mainly specifying which entrance, not a second location for the waiting.

Can I change the word order? For example, Мы ждём друзей у входа в театр.

Yes. Word order is flexible. Both are natural:

У входа в театр мы ждём друзей. (sets the scene first: “At the entrance…”)
Мы ждём друзей у входа в театр. (starts with “we,” more neutral)

Russian word order often reflects what you want to emphasize (topic/focus), not different grammar.

Is мы necessary? Could I just say У входа в театр ждём друзей?

In many contexts, мы is optional because the verb ending already tells you it’s “we”:

ждём = “we wait/are waiting”

So У входа в театр ждём друзей is possible in conversation, but it can sound a bit more casual and context-dependent. Adding мы makes it clearer and more neutral.

Why is it ждём and not something like “we are waiting” with a separate verb “to be”?

Russian normally doesn’t use a separate present-tense “to be” (am/is/are) in sentences like this. The present tense is expressed by the verb alone:

мы ждём = “we wait” / “we are waiting” (context decides)

What tense/aspect is ждём? Does it mean “we will wait” too?

ждём is present tense, imperfective (from ждать). It means:

“we wait” / “we are waiting” (now), or sometimes “we wait (habitually)”

For a clear “we’ll wait (and then do something / for a while)” you often use a perfective form, e.g.:

мы подождём друзей = “we’ll wait for the friends (for a bit)”

Why is it друзей and not друзья? What case is друзей?

друзей is accusative plural for an animate noun—and for animates, accusative plural = genitive plural in form.

Dictionary form: друг (friend)
Plural nominative: друзья (“friends” as the subject)
Plural accusative (animate): друзей (“(we’re waiting for) friends” as the object)

So ждём друзей = “we’re waiting for (our) friends.”

Does ждать always take друзей (genitive-looking form)? Could it ever be different?

With people/animals, you’ll typically see the animate accusative form (which looks genitive in plural and for masculine singular):

ждать друга (accusative = genitive form)
ждать друзей

With inanimate objects, accusative looks like nominative:

ждать автобус (“wait for the bus”)

Also, under negation or in some stylistic contexts you may see genitive used, but for “waiting for friends” this form is the normal one.

How do I pronounce ждём and what’s the deal with ё?

ждём is pronounced with yo: roughly zhdyom (one syllable).
The letter ё is often written as е in texts (ждём → ждем), but the pronunciation is still ё in this word.

What are the stresses in the sentence?

Common stresses:

у вхо́да
в теа́тр
мы ждём
друзéй

So: У вхо́да в теа́тр мы ждём друзéй.