Making it simple, localhost as a web address connects to your local machine, where in this case you have Apache installed as web server. The second part, :8080, means connect to port 8080 of that web address. If you don't specify it, your web browser will connect to the default webserver port, which is port 80.
Employer Identification Number. The Employer Identification Number (EIN), also known as the Federal Employer Identification Number (FEIN) or the Federal Tax Identification Number, is a unique nine-digit number assigned by the Internal Revenue Service (IRS) to business entities operating in the United States for the purposes of identification.
A federal employer identification number, or EIN, is a nine-digit number the IRS assigns to businesses for tax filing and reporting purposes. The IRS uses the EIN to identify the taxpayer. EINs must be used by business entities --corporations, partnerships, and limited liability companies. However, most sole proprietors don't need to obtain an EIN and can use their Social Security numbers instead.