Gacha in Uma Musume
Gacha is fully separated between support cards and characters. There are always two banners active (one for supports, one for characters), called pickup banners. On every pickup banner, at least one support/character will be on a rate up.
The gacha rates in Uma Musume are 3% for an SSR card (or a 3☆ character), 18% for an SR card (or a 2☆ character), and 79% for an R card (or a 1☆ character). Pulling 10 at once will guarantee an SR (or a 2☆) or higher on the 10th pull.
Note that the rates shown in-game are rounded to three decimal places, while this page lists the exact values, so there can be some very small differences between the numbers.
Apart from the two pickup banners that are always active several special banners also exist. Some are time-limited some can only be pulled on once. Any gacha tickets you obtain are also used on separate banners.