to kiss: to press the lips to a person or thing as a sign of affection, greeting, or homage
This is the ordinary word for kissing in the Hebrew Bible, and almost every time it appears it means a literal kiss. What varies is the reason for the kiss, and the range is wide. Most often it is the warm kiss of family and friends: a father blessing his son, brothers reunited after years apart, a parting kiss between people who may never meet again. The same act can also seal a solemn moment, as when Samuel kisses Saul after anointing him, marking him out as ruler.
Beyond affection, a kiss could express loyalty or submission to someone in authority, which is why the psalmist can command the nations to "kiss the Son" as an act of allegiance. The same gesture, aimed at an idol, becomes an act of false worship: kissing a statue of Baal or blowing a kiss toward the sun and moon were recognized ways of paying homage to a god. In love poetry the kiss is frankly romantic. And once or twice the word turns figurative, as when righteousness and peace are pictured kissing each other, or an honest answer is called a kiss on the lips.
The act is simple; the meaning comes from who is kissing whom and why. Reading the surrounding scene, rather than the single word, is what tells you whether a kiss is tender, ceremonial, devotional, or romantic.