The two kinds of coin used on Everskies are Stars and Stardust, which operate kind of like dollars and cents. At the moment 1 Star is usually traded for about 300 Stardust, which is insane but there's a reason for it.
Some time last year or maybe this one I don't know and it's not that important, a kind of bot account was introduced to Everskies that bought Listings (items being sold by users) at unreasonably high prices, and tipped large amounts into Tip Jars. This unbalanced the ratio and made Stardust worth less, which meant that the Exchange feature was disabled. No word was given as to how long it would be disabled, as of 28/06/24 it still don't work. Inflation crisis isn't just limited to the real world I guess.
At the moment, the easiest way to earn money is by playing games or watching ads. You can go here to play games:
There are six different games you can play, although one earns you no money and is more a social feature than anything else
My preferred games are Tic-Tac-Toe, which earns you 500 Stardust for winning a game, and Memory, I forget how much exactly you get but it's pretty solid amount at level 10.
Tic-Tac-Toe on Everskies is played by having 9 boards set up into a 3x3 square. You play as either Planets or Stars. You can place your piece in the 3x3 square which correlates with the place your opponent last put their piece. If they place theirs into the bottom left slot of their square, you can now place into any slot in the bottom-left square, provided it isn't occupied. To win a square, you have to get 3 in a row in it, and to win the game, you have to get three squares in a row. If you place your piece in a slot which correlates with a square that has already been won, your opponent can choose which square to place in. If you place your piece in a slot which correlates with a square that has no slots remaining but has not been won, your opponent cannot place their piece and you will both have to leave.
Many beginners are tempted to place into the middle slot every time it is available. Don't do this. After a while you will work out your own strategy, but until you do I would recommend putting them into a square they have never placed in for the first 9 turns, and then working out where to place them next based on what squares they are in danger of winning, and how much of an issue it is.