Let me give you a few scriptures all the way back to the Book of Genesis that will give you a little help in understand this week being a 7 year period.
Genesis 29:27-29 Fulfill her week, and we will give thee this also for the service which thou shalt serve with me yet seven other years. And Jacob did so, and fulfilled her week; and he gave him Rachel his daughter to wife also. And Laban gave to Rachel his daughter Bilhah his handmaid to be her maid.
The word translated weeks in the English language comes from the Hebrew word Shabuwa. Shabuwa can mean seven. period of seven days or period of seven years. (Strongs concordance #7620) We can see from the Genesis scripture above that it is not abnormal for 1 week to be a period of 7 years. Daniel 9:24-27 gives a list of events that will take place through the process of these 70 weeks. Daniel lived about 600 years before Jesus came the first time and was crucified and the events listed in these verses of Daniel cover a time period all the way to the crucifixion of Jesus so we know that it is impossible for this to be a literal 70 week period.
Daniel 9:24-27 speaks of a 70 week period which is 70 weeks of 7 year periods. 70x7=490 years 483 of those years were completed, starting with the rebuilding of the temple by Nehemiah (Daniel 9:25) and completed at the time that Jesus was crucified (Daniel 9:26) almost 2000 years ago. The bible informs us that there will be a gap in time between the 69th week and the 70th week. This 70th week will be the 7 year period that ends the 6th millennium and ushers in the Second Coming of Jesus Christ which will begin the 7th millennium and the 1000 year reign of the LORD as mentioned in Revelation 20:1-4.