It's not clear what terms you need help with, so I'll just go through the numbered things...
- Employers can't stop employees from trying to form unions.
- They can't punish employees if the employees "tell on" the company for violating parts of the act.
- They can't try to control the union by giving it money.
- This one sounds more like something the union can't do -- it can't force the employer to boycott any other business. What this means is if the union at Company A doesn't like Company B, it can't tell Company A to stop doing business with Company B.
So is that what you wanted?