Learn Hardcore Czech: Možná večer jedu domů autobusem, protože mám lístek se slevou. - Maybe in the evening I will go home by bus because I have a ticket with a discount.

Možná is an adverb meaning perhaps/maybe. Placing it at the start of the sentence indicates that what follows is a possibility rather than a certainty.

Why is jedu (present tense) used even though it refers to the future (this evening)?

With Czech verbs of motion, the present tense can express a planned or scheduled future action. So jedu here means “I’m going (this evening).” If you want to emphasize the future more strongly, you could use the future tense pojedu, but in everyday speech jedu is perfectly normal.

Why is večer not preceded by a preposition like v?

Večer is an adverbial accusative of time. In Czech, many time-of-day words (e.g. ráno, odpoledne, večer) appear without a preposition to mean “in the morning/afternoon/evening.”

Why is it domů and not do domu or just domu?

Domů (with ů) is the directional adverb meaning home/to home.
Do domu means into the house (focusing on entering the building).
Domu without the accent is the genitive form of dům (“of the house”).

Why is autobusem in the instrumental case?

To express means of transport, Czech uses the instrumental case. Therefore autobusem literally means by bus.

Why is there a comma before protože?

In Czech, a comma separates a main clause from a subordinate clause introduced by conjunctions like protože (“because”).

What does se slevou mean, and why is slevou in the instrumental?

Slevou is the instrumental of sleva (“discount”).
The preposition s (“with”) requires the instrumental case.
Before a word beginning with s, s changes to se for easier pronunciation: se slevou = with a discount.