Days of the week in Hindi
Seven words, one shared ending. वार means day, so every weekday is a name plus that ending, which makes the whole set easier to hold than it looks on first sight.
The seven
Two of these have a common everyday alternative. Sunday is often इतवार (itvaar) in speech, and Thursday is sometimes बृहस्पतिवार (brihaspativaar), which is the fuller, more formal name. Both of the forms in the list above are understood everywhere.
Today, tomorrow, yesterday
This is the part that surprises everyone. Hindi measures distance from today, not direction. कल is simply the day next door, and the verb tense tells you which side you mean.
Using them in a sentence
Notice को after the day. Hindi marks the day you are pointing at with को, the way English uses on. सोमवार को means on Monday.
Worth pairing with
Day plus time of day covers most of what you need to make a plan, and making a plan out loud is the first conversation that feels like it belongs to you rather than to a textbook.