A convex pentagon has no angles pointing inwards. More precisely, no internal angles can be more than $180^o$.
The pentagons in the figure, are $ABDFH, CDFHB, EFHBD, GHBDF, ACDFG, CEFHA, EGHBC, GABDE, BDEGH, DFGAB, FHACD$ and $HBCEF$. Clearly, these are $12$ in number