dest = sqrt(source)
The sqrtss, sqrtsd, sqrtps, and sqrtpd instructions computer the square root of the source value (second operand) and store the result(s) in the destination operand. There are also vsqrtss, vsqrtsd, vsqrtps, and vsqrtpd on CPUs with AVX instructions which can compute multiple values at once. Behaviorally these instructions are similar to the various add instructions should you wish to see more details.
sqrtss xmm0, xmm1 ; xmm0 gets 32 bit sqrt of xmm1 sqrtsd xmm0, [x] ; xmm0 gets 64 bit sqrt of x sqrtps xmm0, [rdi] ; xmm0 gets 4 32 bit sqrts of [rdi] sqrtpd xmm0, [x+4*rcx] ; xmm0 gets 2 64 bit sqrts of array x vsqrtps ymm3, ymm15 ; ymm3 gets 8 32 bit sqrts of ymm15 vsqrtpd ymm3, [x] ; ymm3 gets 4 64 bit sqrts of array x