Dim lRow As Long
    Dim i As Long
    Dim iDate As Long
These declare three variables (names I'll use to store values) and their data type Long (Long is any number between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807)

The code to send the email copies visible cells this code:
Application.ScreenUpdating = True
makes sure that the screen updating is turned on so that later when we copy cells they ones mark hidden will update to hidden.

lRow = Range("A65536").End(xlUp).Row
Sets the variable we declared in the first step to the last occupied row in column A. If there is data in cells in column a clear down to row 9999 then lRow = 9999.

For i = 4 To lRow
Starts a loop that steps i (another variable declared in step one) from 4 to whatever lRow is set to (our example was 9999 but it changes based on the number of cells occupied.

 If IsDate(Range("A" & i).Value) = True Then
This asks a question if range Ai (remember the value of i varies based on which step of the loop we're in, it has the effect of checking every occupied cell in column) is a date. If this is true then we know it could be one of the cells we want to copy. If it is then we:

iDate = DateDiff("d", Date, Range("A" & i).Value)
set the last variable we defined to a number which is the difference between todays day date, and the date in the stepped range we're looking at.

If this comparison is more than 0 (the date is not in the past) and less than 7 (its within our timeframe therefore we want to keep it in the eamil) we can sort them out with 
If iDate < 0 Or iDate > 7 Then
All the rest of the cells we will make invisible so they are not part of our email. We can accomplish this with: 
Cells(i, 1).EntireRow.Hidden = True
The rest of this happens in code that you didn't quote -the call sendemail is another Sub with a function that creates an HTML object consisting of the visible cells in the selected range. Lastly we make all cells visible again so they can be edited if need be.

I hope this answers your question, if it does please mark that thread as [SOLVED]