Re-enter is enter once again. For example: you see big dot for sell on close bar. In previous bar. So, you may open sell order. If you set re-enter as true (or 1) in indicator's setting so you will see re-enter (x) on the chart. It means that you may open sell once again if main order was sell for example.

In asctrend system we are using this re-enter. You may look at my statements on this thread and I always used re-enter. Did you had sell? So, you will have the other sell. Two orders. One was opened according to the dot (main signal) and the other one may be opened on re-enter.
Re-enter. Means: enter once again by new order without closing the old one.

But, to say a true, i don't think that this system will be profitable without filtering the signals. may be, on D1 or W1 timeframe and with re-enter only as classical asctrend. But we will need the other indicators as well in this case (NRTR and so on).