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.
Generally, an EIN number is used to file various IRS business tax returns, open business bank accounts, obtain business licences, etc. The federal tax identification number is nine (9) digits long and is issued in the following format: XX-XXXXXXX. Essentially, it is similar to a Social Security Number (SSN) for an individual, but an EIN number is for businesses and entities.