Why Symbol rate, also called baud rate, counts how many times per second the transmitted waveform changes state (its amplitude, phase, or frequency) to carry information. Each of those states is a symbol, and depending on the modulation a single symbol can carry one bit (BPSK) or several bits (QPSK carries 2, 16-QAM carries 4). So bit rate equals symbol rate times the number of bits per symbol, and the two are equal only for simple binary keying.
Watch out Characters per second describes throughput or the character rate, which is further removed still, since overhead bits, framing, and error correction coding all sit between the symbols on the air and the characters delivered to the user.
Baud = changes per second on the air, not bits or characters. Bits = baud x bits per symbol.