If it comes from Latin (as it seems to be) the stress is on the A and you should pronounce it something like ah-qui-lah (with the "qui" sounding something like

If it comes from Latin (as it seems to be) the stress is on the A and you should pronounce it something like ah-qui-lah (with the "qui" sounding something like "quick"). But I'll wait for the author to correct me :)