In this bleak poem, Kamala Das describes her relationship with her lover, which is based on physical coupling. She experiences her body as scorched and consumed by her lover in unpleasant ways: his kisses are like the "burning mouth" of the sun (she repeats "burning" twice in the opening) and her lover's "limbs" like "carnivorous plants" reaching out to devour her. Neither image is pleasant or inviting. She calls her "lust" a sad "lie": in her imagery she appears consumed rather than fulfilled; she realizes this relationship is not what she would like it to be.
Yet she admits that while her mind is "moody," not happy with the mere bodily component of her relationship, there is a certain "pleasure" in the physical relationship: she calls it "deliberate gaiety" but at the same time undercuts the idea of pleasure with her image of it as "harshly" trumpeting into the room.
Her imagery continues to convey the destructive quality of her relationship: all around her is a malevolent world. Crows fly like "poison," she hears the cries of "corpse bearers," her nights are "moonless" and she is "sleepless." She questions this "skin communicated thing" that she can't call, at least in her lover's presence, love.
The poem shows the dehumanization of the decoupling of love and lust as the narrator experiences it. The narrator would like more than the bodily relationship that leaves her feeling used up, moody and despondent. What she has makes her feel, by implication, poisoned and corpselike. At the same time, she is afraid to bring up the idea of love "yet" to her partner. The word "yet" is possibly the most poignant word in this poem: despite the bleakness the narrator experiences in her relationship and despite her seeming inability to talk to her lover and express her feelings, she still ("yet") longs for the lust to transfigure into love. We, as readers, might see more clearly than she does that this is not likely to happen, given the relationship she describes.
Good poems are up to interpretation. You need to read the poem and interpret it yourself (see the link). This is my interpretation. The author may have meant something completely different. At a different time in my life, I may have interpreted it differently.
The start of the poem compares the heat of a kiss with the heat of the sun on a hot day and the way the warmth reaches out and penetrates through her, exposing the lie she is telling herself.
She then tries to convince the reader, and herself, that it isn't love, it's just the moment and the act itself "... isn't each embrace a complete thing ...", as she tries to ignore her feelings and simply enjoy the moment.
The cruelty of life goes on without him through the day and night (crows like poison on wing, and a funeral procession singing "praise the Lord"), while she can't sleep because of thinking of him.
The poem ends with her realizing that she still doesn't trust herself and what her body is telling her ("... a million questions awake in me, and all about him ..."), so she can not reveal how she feels to him, even though her entire body knows the truth.