Sure.
DFF is a Dtype FlipFlop. A basic gate level element that can store 1-bit of information. This we also call as register. Because it can register(store) 1-bit of data for every clock it receives. A DFF works only if clock is provided. If the clock is @50MHz, then you can say that you are registering data @50MHz rate. A Xilinx D FF can have many types, for example DFF with set\reset, DFF with clock enable, etc. These are low level components that you may find inside the FPGA chip.
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