If a company is trading on what is called a 'forward multiple' its shares are valued at a multiple of its prospective earnings rather than the value of its underlying assets. (See also PE ratio.) For example, shares may be valued on a forward multiple of 8 times earnings if respectable growth is anticipated.
Companies can be valued in a number of ways. Forward multiple is a sexy way of saying that the total worth of a company is a multiplier of its projected annual profits. E.g. Company A makes $1 Million per annum. Its total value is $10 Million. It has a forward multiple of 10 ($10 Million divided by $1 Million) Easy... now go and impress your friends.