1 Album sale can consist of just buying the entire album [1 Copy] digitally on iTunes, Amazon or the Artist Store. You can also buy a copy in stores if its available. You can also look for the vinyl if its available.
Another way to buy an album or to get album sales to count is to buy at least 10 songs separately from the same album. No correct order is needed. 10 of the songs out of the total amount will also count as an album sale. 10 of your favorite songs from the same album.
Streaming is essential now in this day and age for artists. If you don't have money to buy streaming can substitute for buying. For 1 single song 150 streams = 1 unit. If you stream a song 150 times it's the same as buying the song once on iTunes or Amazon. if you stream an album 1,500 times it'll count as you buying the album on iTunes or amazon. 150 streams = 1 Single Unit. 1500 Streams from the same album = 1 Album sale.