An important part of developing emotional literacy is about helping your child to understand that all feelings are valid. We should never tell anyone they have no right to feel any particular emotion. Emotions can't be stopped or at least can catch us off guard. (It's the choices we make about how to behave when we are feeling any particular emotion that we can have some control over not what we feel and when we feel it). The easiest way to validate emotions is to is to say things like:
I can see your are angry
I would be excited too if....
I can understand why you feel sad
Your face is telling me you are probably disappointed
However, something that can get in the way of us managing our child's feeling effectively is to do with how shameful we were made to feel as a child when we expressed certain emotions. For example, if as a child when you became jealous and one of your caregivers attached shame to that feeling (by making you feel less lovable for having expressed jealousy) unless you had really thought about your relationship to jealousy, you are likely to have a strong and shameful reaction to your own child expressing it. When we feel strong shame, we are less likely to make careful choices about how to react and more likely to become defensive or have exaggerated responses. This will mean we will not be so effective at managing our child's uncomfortable feelings or worse still, could initiate your child attaching feelings of shame (unworthiness) to feeling jealous.
While jealousy isn't a comfortable emotion, we should be able to feel it without it challenging our baseline self-worth. Healthy emotions are transient and should not have a hugely detrimental impact on how we see ourselves. This is not to say we can't learn to manage jealousy better but it is part of the human experience and acknowledging it rather than trying to suppress it, gives us more chance of developing a better relationship with it.
Other feelings that sometimes have strong shame attached to them include anger (especially for girls), vulnerability (especially for boys), feeling defiant, feeling proud and anxiety. Awareness of your own responses to experiencing different emotions can help you more effectively support your child to manage their emotions.