What was Lady Mary Wroth trying to communicate in "Sonnet 11?"
The language of Lady Mary Wroth can be hard at times to understand. The key to reading her poetry lies in what the word appears to look like (in Standard English). For example, "opresse, "paine," and "griefe" are written using traditional English (England) spellings. Some words prove to be far harder. For example, "Loue" is obsolete for love. "Moue," if compared to "Loue," means move. "Giue" means "give" (as it works if used as a replacement in the poem). As a suggestion, always have a dictionary (bound or electronic) close by when reading early texts.
As for what the poet is trying to convey in "Sonnet 11," the form of the poem is important. A sonnet tends to offer the reader a problem or concern and suggests or offers an answer in its final few lines (typically the ending couplet).
The message in most sonnets is similar as well. Many are about being in love, lost love, or unreturned love. In the case of Wroth's "Sonnet 11," the poem speaks to a love being unreturned. The speaker is asking another to make the pain end (mental pain of love). The first twelve lines tells of the pain the speaker is going through (because of love), and the last two lines (the couplet) speaks to the solution--the speaker needs the other to release her ("her" being an assumption regarding gender of the speaker for clarification) from the binds of love. It will be only then that she will be able to move on.