There are two categories of terms to worry about - those that you'll understand easily by reading below and those that you'll probably need an attorney to explain. Needless to say, we are going to cover the former here.
Most investors are going to expect you to be fluent in at least the common venture investment terms below.
When you hear about companies raising money on a "big valuation" they are referring to the projected value of the company that was agreed upon when the investment was made. Note we're saying "projected value" because most valuation amounts are highly speculative (read: “made up”) in the venture investment world.
You'll commonly hear two methods for expressing the valuation of a company:
Pre-Money Valuation - The amount the company is valued at before money is invested. If you valued your company at $5 million, the Pre-Money Valuation would be $5 million, as in "before money was invested."
Post-Money Valuation - The amount the company is valued at after the money is invested. If your company was valued at $5 million before the investment, and the venture investment was $1 million thereafter, the Post-Money Valuation would be $6 million.
The effect of giving someone else part of the company's stock is considered "dilution". It means that you are diluting your equity stake to make room for someone else. When you're worried about "giving away the company" that's called dilution.