Question: What does this mean:

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> Any future UK visa applications you make will be considered on their individual merits.
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Answer: 
It means that if you make another application, that application will be given its own assessment to decide if it will be granted. Just because a previous application failed it doesn't mean the new one will fail.

HOWEVER...

Your previous applications are going to be part of assessing the new one. If your new application contains information that contradicts a previous one, or if you made false statements on a previous one, or the changes in circumstance are implausible, then that will have an effect on the new assessment. They can use information you provided in a previous application in making the new assessment.

Also assessments are fairly standardized. So if you make an application that fails, and then submit a virtually identical application in which your circumstances are the same, it is very likely that one will fail too.
‘Merit’ means ‘worth’ - that is, each application is assessed based on what is stated in and provided with that application.