to come into possession of something: to buy it, or otherwise get and hold it as your own
This is the everyday sense of the word and by far the most common. Its center of gravity is simply coming to own something, whatever the means, and English Bibles reach for a whole family of words to carry it: "buy," "get," "purchase," "acquire," "gain," "own."
Most often it is a plain commercial purchase, paying a price for a field, a person, an animal, or food. The classic scenes are Abraham buying a burial cave and Boaz buying Naomi's land along with Ruth, and the word naturally pairs with its opposite, selling (מָכַר). But it stretches well past the marketplace. Proverbs uses it again and again for getting wisdom and understanding, things no money can buy but that a person can still make their own by effort. It can name the settled state of owning as well, as when an ox knows its owner.
The same word also carries a redemption note when God is the one acquiring. At the Red Sea and in the Psalms, God is said to have gotten Israel as his own, and later Hebrew even uses this word where earlier writers would have said redeem (גָּאַל) or ransom. All of these are angles on one idea: taking lasting possession, so that the thing is now yours.