^ It goes something like this iirc. im gonna bold the "factual" parts and the non bolded parts are just examples.
slots - these are basically time slots, which are the times that each girl does their handshake event. how many tickets are within a slot? no one really knows.
for example, a slot could be 1 hour long, and fans have said each ticket is worth 10 seconds, so let's say paruru, has 5 slots to sell out, which means she will be doing handshakes for 5 hours broken down into 5 slots. We could assume that's 360 tickets in an hour (slot) x 5 slots = 1800 tickets in 5 slots? For the members who sell extremely quickly like sayanee and sakura, there are 25 slots, so if 1800 tickets are sold in 5 slots (which is the amount that they do a day i've heard?) times by 5, that's 9000 tickets in 25 slots. again, this is just an example.
numbers inside () - Number of slots almost sold out
some slots are "almost" sold out, which i assume means there are only like less than 20 tickets left? in that case they would put (x) at the end of the numbers to signify that. i think its more important for members who have almost completely sold out, for example Nakai Rika has 22/25(1), meaning that she could sell out in the next round so if you want her tickets, its like a warning to hurry up lol.
numbers inside circle - The round the girl sold out on, for example, Paruru only had 5 slots due to her graduation, so she sold them all out during the first round, hence her numbers appear as 5/5①. Sayanee sold out her 25 slots during the first round, so her numbers appear as 25/25①. Mayu and Yukirin sold out on the 4th round so their numbers appear as 25/25④, and so on.
though, i've never been to a hs before so krusha can probably explain this better