what does "further down the line" mean?
so they can get a basic understanding of what's involved in the study of the subject further down the line,

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Answer

"further down the line"- later in the future.

Answer

It means after something has progressed. 
Looking into the future.

"You will be working on the reception desk, and further down the line - say in 5 years - you may be working in the management team".

None of your female pen-pals know that?