If something is streaked, it has lines or marks of a different color or texture on it.
Streaked things can look interesting or messy, depending on what they are.
Examples:
The sky was streaked with red and orange at sunset.
She streaked her hair with blue dye.
The cat streaked across the room.
The ice cream was streaked with chocolate sauce.
The superhero's costume was streaked with bright colors.
The artist streaked the canvas with bold brushstrokes.