Scalar quantities have magnitude only, such as length, time, temperature. Vector quantities have both magnitude and direction, such as displacement, velocity, force. There are two main types of errors in measurement - systematic errors and random errors. Systematic errors consistently shift measurements in one direction, such as zero errors or calibration errors. Random errors vary unpredictably between measurements, caused by factors like human error or environmental changes. Precision refers to the consistency of measurements while accuracy refers to how close measurements are to the true value.