Blood clots will do this. Cutting off blood flow while also increasing blood pressure. Also, if the viscosity (thickness of the blood) is thick which will slow down the flow and cause the body to use more effort to pump blood.
It means that two or more cells connected together.
You can look at the word 'cell' and 'conjunctions' separately. 'Cell' is a tiny particle. 'Conjunctions' means 'two or more things connected', so just put the two meanings together.
Hope this helps. :)