Incorrect. The + or - doesn't indicate separating or applying, it indicates how many degrees from exact the aspect is and whether it's fewer or more degrees than would take to be exact.
If it's a +, the planets are slightly more than however many degrees apart they would have to be in order to have an exact aspect, and the - means less. For example, let's say the aspect is a square. If the planets are 92 degrees apart, the square is +2. If they're 87 degrees apart, it's -3.
That alone doesn't tell us whether the aspect is separating or applying. That part depends on whether the faster moving planet is earlier or later in the zodiac than the slower moving one. If one of the planets is retrograde and the other direct, then we look at whether the retrograde planet is backing into the direct one, or away from it.
Let's say we've got a square of 92 degrees between the moon at 27 Libra and the sun at 25 Cancer. The moon moves faster than the sun, and since it's 2 degrees past the exact square, the square is separating. But suppose the moon were at 23 Aries instead. They would still be 92 degrees apart, making it a +2 square, but in this case, it would be an applying square. The moon hasn't yet reached 25 Aries, where the square would be exact.