'Get out' in this context means get a result. The phrase basically means that If you try hard, you'll succeed, and if you don't try hard, you should expect to fail. You put effort in, and get results out. Not a very good explanation but I hope it helps.

Thank you for answering

It means receive or obtain. You will get out, receive, obtain equally to what you put in, invest, give. You will get (out) a good grade if you invest time in studying. You will get love if you give love. This saying can also be expressed as: What goes around, comes around. This is karma.