Below a brief definition of Scalars, Vectors and Matrices as used in linear algebra.
Scalars
A scalar is a numbers. Scalars are what we are used to. Any real numbers (e.g.: 1, -2 or 0.3456) are scalars.
Scalars are quantities that have positive or negative numerical values (like distance, speed, temperature, mass, volume, etc) and have a magnitude only.
Vectors
A vector is a lists of scalars arranged in a row or column. Vectors have positive or negative numerical values (like distance, speed, temperature, mass, volume, etc) to describe a magnitude and direction, e.g. force will have a strength and a direction in which it acts.
Matrices
A matrix is an array of scalars arranged in one or more rows and one or more columns. A vector is also a matrix, because a matrix can have just one row or one column.