Lump on vulva

my 2 year old border collie developed a lump after coming off her second heat (she is not yet spayed). The lump is soft and she is not licking it or acting any differently. She is also toileting normal.

Hello!  I would strongly advise showing this lump to your vet, who will start to establish whether it is a lump of the inner vulva poking out, or of the skin.  Reasons for lumps can include tumours (sinister or benign), demodex mites, warts, hormone-related changes, cysts and so on.  If your vet isn't sure, they may recommend a biopsy and they may also be keen to carry out that spay, as spaying can reduce a dogs' risk of cancer going forward.