$*p$ in $\text{int} (*p)[10][5]$ has higher priority due to parenthesis. So, it’s a pointer to 2d int array of dimensions [10][5].
p is given as 1000. $p + 1$ is equivalent to saying $p + 1*sizeof(*p)$. $*p$ means the type pointed to by the pointer p.
Since p points to int array of size $10*5$, $sizeof(*p) = 10*5*sizeof(int) = 10*5*4 = 200$, we have,
$p+1 = p+1*sizeof(*p) = 1000+1*200 = 1200$