docs(css): add skewY() term entry

content/css/concepts/transform-functions/terms/skewY/skewY.md

@@ -0,0 +1,44 @@
+---
+Title: 'skewY()'
+Description: 'Skews an element along the y-axis in a two-dimensional plane.'
+Subjects:
+  - 'Web Design'
+  - 'Web Development'
+Tags:
+  - 'Functions'
+  - 'Positioning'
+CatalogContent:
+  - 'learn-css'
+  - 'paths/front-end-engineer-career-path'
+---
+
+The **`skewY()`** function skews an element along the vertical axis by shifting it up or down based on the specified angle.
+
+## Syntax
+
+```pseudo
+transform: skewY(<angle>);
+```
+
+**Parameters:**
+
+- `<angle>`: Specifies the angle of the vertical skew. Accepts angle units such as `deg`, `rad`, `grad`, or `turn` (e.g., `20deg`, `0.2rad`).
+
+A positive value skews the element so that the top shifts to the right and the bottom shifts to the left. A negative value skews it in the opposite direction.
+
+**Return value:**
+
+Returns a `<transform-function>` value that represents a 2D vertical skew transformation and can be used with the `transform` property.
+
+## Example
+
+The following example skews the `.rectangle` element along the y-axis by `20deg`:
+
+```css
+.rectangle {
+  height: 100px;
+  width: 200px;
+  background: blue;
+  transform: skewY(20deg);
+}
+```