Physics is the understanding of properties of nature, various phenomena. The matter, elements, that are around us exist in different states and have properties.
These properties are expressed often in physical quantities, like volume, pressure, size, color, mass, density, speed, acceleration, force, momentum, electric field, magnetic strength, resistance etc.
These physical quantities are related by various laws. These relations are expressed by mathematical formulas. The various behaviours of solids, liquids, gases are all inter-related.
In a practical problem these relations are expressed in terms of unknown variables. Then they are solved to get their values.
Science is all about being objective, rational, quantitative, precise... For being quantitative and precise , we need mathematics.