A Pip represents the change in value between two currencies. For example, if the EUR/USD moves from 1.2250 to 1.2251 it has moved by 0.0001 or one Pip.
A Tick is similar to a Pip, but it may not measure every increment equally. For example, A Tick on one instrument may be measured in increments of 0.0001 whereas another instrument may be measured in increments of 0.25. A Tick is simply the smallest increment a particular instrument can move in.
A Point is a shift in the dollar amount. For example, if a share price went from $25 to $30, traders would say it has moved 5 points. For FX a point is used to refer to the 5th decimal place.