What the card describes as a feeling
The emotional state is containment. A person reading here may be very aware of what they feel and has decided that you do not get to see it yet. That decision may be caution, may be self-protection, and may simply be temperament.
People on the receiving end tend to fill the silence with whatever they most want or most fear. The card does not tell you which is warranted. It only says the information is being kept, which is a fact about behaviour rather than about depth.
Upright
Upright the reading is a considered reserve. There is feeling and there is a reason for the quiet, often a reason the person would consider reasonable if you heard it. Watching rather than acting is the usual posture.
This is one of the least performative feelings in the deck. Nothing here is being demonstrated for effect, so there is very little for you to read from the outside, which is the difficulty of it rather than an accident.
Reversed
Reversed the containment breaks or curdles. One reading is secrecy that has become active concealment, where the withholding is now doing work. Another is a person overwhelmed by feeling they have refused to name, so it leaks out sideways as mood.
The third and kindest handling is disclosure, feeling finally about to be spoken. Whether the reversal points to a wall or a door depends on whether the rest of the spread is closing or opening.
Outside romance
A friend reading as this card may be going through something and has not decided to tell you. In a work setting it often marks someone who has formed a clear opinion of you and keeps their own counsel by policy. Within a family it fits the relative everyone assumes is fine because they have never said otherwise, which is not the same as being fine.
What a feelings position can and cannot tell you
Reading cards for what a person feels is a recent habit. The layouts that formalised positional meaning were built around events, and the feelings slot was grafted on later. What the card offers is a quality; the person is supplied by the reader, not by the deck.
So a card cannot report on someone's inner life. It gives you a description you then aim at a name. When that description is treated as evidence, the reading has quietly replaced a question you are entitled to ask, and the tarot has become a way to avoid asking it.
With this card in particular the response is obvious and unwelcome. If you want to know what is being withheld, ask, and accept that a reserved person may decline. The card is describing someone who will not volunteer it.
Questions people ask about this
Does the High Priestess mean they have feelings for me?
It describes feeling kept private rather than feeling of a particular kind. What is being withheld is not specified, and the card cannot name it.
What does the High Priestess reversed mean as feelings?
Either concealment that has become active, feeling leaking out unnamed, or something finally about to be said. The spread's direction decides which.
Is this card a sign to wait?
The tradition often reads it that way. Waiting indefinitely on a card rather than on a person is a different matter, and not one the deck recommends.