It's not really Latin. It's English legalese, written by an English scribe, thinking in English and 'translating' word-by-word as he went because documents at the time had to be in Latin.
I don't really understand it but it's something like:
To some [people] by the name of William Merwood Jr, son and heir of the said William, in short his nominee*, and Johanna, wife of his, and one of the daughters of the said Humfrey.
*I think nominatus means "designated heir nominated by the deceased".
PS. Add the LATIN tag to your post so that people following it will see.