Questions & Answers about Wir treffen uns heute Abend in der Kneipe.
Why do we use the reflexive pronoun uns here?
When a group of people meets up with each other, German uses the reflexive verb sich treffen. Without uns, the verb treffen would need a specific direct object, like saying we are meeting someone else, rather than meeting each other.
Why does the time heute Abend come before the location in der Kneipe?
This follows the standard German word order rule often remembered by the acronym TeKaMoLo. Time (Temporal) expressions generally come before location (Lokal) expressions, which is exactly the opposite of the typical English place-then-time order.
Why is it in der Kneipe and not in die Kneipe?
The preposition in is a two-way preposition. Because the meeting is happening at a fixed location (answering the question where?) rather than describing movement towards a destination, it takes the dative case. The feminine article die changes to the dative der.
Could I say am heute Abend instead?
No, the phrase heute Abend (tonight or this evening) functions as a complete time expression on its own and does not take a preposition. You would use am if you were just saying am Abend (in the evening), but adding heute makes the preposition unnecessary.