Yeah the P/E ratio is an important aspect of valuing a company. It is used basically to help you see what a company can earn for you. It is calculated by taking the price of the company and dividing it by the earnings, hence P to E or P/E.
If I offered to sell you my pizza stand on main street in my town for $50,000, and it made $10,000 last year then I would be offering to sell it to you for a P/E of 5.
P/E = 5 divided by 1 = 5
In other words it would take you about 5 years to earn your money back after buying my pizza joint at this price. If the price were lower, or the earnings were higher then the P/E ratio would be lower. Hence it would take less years to earn back your money. That would be nice.
When you apply the P/E ratio to a corporation things are a bit different because instead of buying a whole company you will be buying shares. The concept is the same however. If a company makes $100,000 per year but it is divided into 1000 shares outstanding, then each share will receive $100 in earnings.
$100,000 divided by 1,000 = $100 per share.
We would call this $100 figure "earnings per share" because it is the earnings divided by the total number of shares.
Simultaneously the quoted price of a company you see online and on the news every day is a per share number. It is the price someone paid for a share. If MSFT is trading at $30, that doesn't mean someone bought MSFT for $30, it means that someone bought one share of MSFT for $30 and now owns one 5 billionth of the company or so.
Therefore earnings per share (or EPS for short) is helpful in valuing a company. If EPS is $2 per share and a company is selling for $20, then the P/E ratio is 10. It would take 10 years for the company to pay for itself in earnings.
A lower number is better for P/E. Read some books on investing. They will explain it better.