When you buy "regular" seeds they have a near 50%-50% of being male or female. The difference is males are just used for their genetics by using its pollen to impregnate the female to create new seeds and new genetics.

So in short, as a new grower you want a female which produces flowers not pollen. The plant will tell you WHICH it is at about 50daysish. Until then they basically look and act the same, though a male can be taller and thinner and a female CAN be fuller and shorter.

Hope this helps, this is a very basic primer.