Peh means 'mouth', the personality understood as the soul's means of concentrated expression on the lower astral planes. The personality is a product of Hod and Netzach: The light of Tiphareth is split up into the many-rayed manifestation of Netzach and this division is confirmed by the analytical mental capacity of Hod: The ego is constructed.
While the light of the soul passes into the personality via this symbolic mouth, speech passes out of it. The activity constituting the ego-personality-mouth is the use of language, the splitting up of creation into comprehensible pieces. But speech can be monologue or dialogue, condemnation or communication, a means of isolation or understanding, a barrier or a bridge.
It depends on the degree of mutual fruitation between the mental concentration of Hod and the collective inspiration of Netzach. Consider for a moment the openness of your Solar Plexus chakra.
In tarot, the problem is illustrated by the trump of The Tower, referring of course to the tower of Babel from Genesis where all communication eventually broke down, but also to the ego-personality which may become a fortress against inspiration from our fellow beings.
Only when Hod and Netzach are in perfect sync, the light of Tiphareth will shine into the personality and illuminate our earthly relations, the ego becomes a vehicle for the word of spirit, the tower becomes a house of God, and there is a balance between internal and external impulses. One method is vibrating the words of power taught by the qabalah, concentrated into the mental symbols of Hod and charged with the ecstatic enthusiasm of Netzach.