It means high priestess. Prospective Deva (Pre-Deva) is including the one who was to serve as Deva in few years.
Prior to actual guardianship, 2 to 4 Pre-Guardian priests serve a Deva in a temporarily formed group. Usually, this temporary formation stays for the actual guardianship, so both Devas and priests nervously wish for the perfect match on the day of priest and Deva matching. But not all matching proceed as assigned. As Deva can either reject a priest, or picks out a priest.
The head Deva is Asherah.
They can take advantage of priests if they wanted to, but priests never make move on her. That's forbidden. No matter how desperate priests are, they just don't cross that line.
Not all Priestesses are Devas.
A Guardian priest that desires a Deva will suffer the living hell. But Madonna's Bible wasn't a single verse that prohibited love between a priest and a Deva. But it's forbidden because they need to keep the order within the church body. This means that priest watches for Deva to go to private worship with Patron or other nobles. Babies are sent to the incinerator at birth for being born out of forbidden love between a priest and a Deva. But there is a exception.
Patrons can make a huge donation to the Church of Madonna and private worshiped by Deva as a reward for it. Patrons may use Deva for personal enjoyment, and Devas may be used by several people for business with nobles. One example is Baron Hussadin.
Pre-Devas are wears the dress of airy, made of thin cloth. When they go outside, they ties a violet sash on their waist.
When they becomes Deva, the length of the dress becomes shorter, and the shape of the necklace changes.
Guardian priests never cause any trouble with the Patron's side unless it's an absolute life-and-death situation for the Devas. And then if they fail to comply, they'll face Internal Investigations from the church body.
They can have a variety of sexually transmitted diseases. Because there're even Patron or nobles who're sick in Space disease. One example is Hormah. If their Space disease came out positive, they're sent to Level zero care.
All Devas are required to wear white sandalwood perfume.
As Madonna's birthday approched, they're proposed by their Patrons.