The wedge golf clubs are very hard to understand for the average golfer. They have loft angles and bounce angles and how many do you really need in your golf bag. Titleist Glof Clubs has some information to help.
Most golfers if they are somewhat serious about their golf game will have 3 or 4 wedges. To determine the number you have is up to you, the more wedges the less other clubs you can carry and visa versa.
The Wedges starting with the pitching wedge should be gaped by how far the golf ball travels when struck full swing. If your Titleist Vokey pitching wedge goes 100 yards then your gap wedge should probably travel about 60 yards full swing. And then the high lob Vokey wedge should travel about 30 yards with a full swing.
And boy if that is not a scary shot that takes full concentration, 30 yard to the pin and you swing all in to get it to the pin. If you blade it, bye bye golf ball! that is when you need a low bounce sole or deep grass to get the shot right.