Learn Hardcore Russian: Мы общаемся онлайн вечером.

-ся marks the verb as reflexive/reciprocal. With общаться, it typically means people interact with each other.
The non-reflexive form общать does not exist; the verb is inherently reflexive: общаться.
This verb doesn’t take a direct object. To say who you communicate with, use с + instrumental: Мы общаемся с друзьями.

How do you conjugate общаться in the present tense?

я обща́юсь
ты обща́ешься
он/она обща́ется
мы обща́емся
вы обща́етесь
они обща́ются

Spelling note: after a vowel you write -сь (e.g., обща́юсь), after a consonant you write -ся (e.g., обща́емся).

What tense is мы общаемся? Can it mean both “we are communicating” and “we communicate”?

Yes. It’s present tense, imperfective aspect, and it can mean either ongoing action (“we are communicating”) or a general/habitual action (“we communicate”). Context decides.

How do I say it in the past or the future?