3 Her goodly port, and to their senses vile

port > rank, social station

4 Her gentle speech applied, that in short space

gentle > gracious, courteous; noble; gentle applied > directed that > [so that] space > time

5 She grew familiar in that desert place.

familiar > {On a family footing} desert > lonely

6 During which time the churl, through her so kind

churl > rustic, boor

7 And courteous use, conceived affection base, 8 And cast to love her in his brutish mind;

cast > resolved