放在 (fàng zài) means to put at or place in/on a location. 放 means to put down or release and 在 indicates the location. The typical structure is 把 + object + 放在 + place (把书放在桌子上, put the book on the table). 放在 is used for deliberate placement, contrasting with 扔在 (throw to/leave carelessly). Figuratively it appears in 放在心里 (to keep in one's heart) or 放在首位 (to put in first place).