This video serves as a comprehensive introduction to trigonometric ratios, specifically targeting the sine, cosine, and tangent functions within right triangles. It begins by establishing the foundational concept that similar triangles possess proportional side lengths, meaning their side ratios remain constant regardless of the triangle's size. The narrator, Justin, then introduces the crucial vocabulary required for trigonometry—naming the sides of a triangle (opposite, adjacent, hypotenuse) relative to a specific angle.