as said ,its just a female plant kept in a vegatation stage so you can take cuttings(clones) & grow them.
you can keep a mother plant for years which will eliminate planting seeds(& buying pricey seeds) or obtaining new clones from mates etc.
plus cuttings from a mother have the same genes therefore will grow at same rate ,so will flower at same time & have same yields(give or take a gram or 2
)
its the way to grow, from clones(space permitting). secret is picking a good mother which grows fast & yields high, but that takes time & patience too find, but you'll get there mate
hope explains it a little more
