Here's the actual text of the speech:
If then true lovers have been ever cross'd,
It stands as an edict in destiny:
Then let us teach our trial patience,
Because it is a customary cross,
As due to love as thoughts and dreams and sighs,
Wishes and tears, poor fancy's followers.
I would "translate" this to mean:
If true lovers are always prevented from loving each other
That must just be how fate is
So we have to be patient
Because this is a common problem
It goes along with love just as much as thoughts, dreams, sighs
Wishes and tears -- all just part of love
This speech is given after Theseus the duke tells Hermia that she must marry Demetrius because that's what her father has said she has to do. She's talking to Lysander, who she truly loves, and they are commiserating about the decision.