このドレスはいつごろできあがりますか。

this (something or someone close to the speaker (including the speaker), or ideas expressed by the speaker)

dress

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

about when; how soon

to be completed; to be finished; to be ready (e.g. to serve or eat); to be very drunk

indicates a question (sometimes rhetorical); or; whether or not; some- (e.g. something, someone); indicates doubt, uncertainty, etc.; emphatic prefix; suffix forming adjectives or adverbs; in that way