The Earth's axis of rotation is tilted with respect to its orbital plane around the Sun. This tilt is known as the Earth's axial tilt or obliquity. The current axial tilt of the Earth is approximately 23.5 degrees. Therefore, we can say that the Earth is tilted by about 23.5 degrees with respect to its orbital plane.
The orbital plane of the Earth around the Sun is called the ecliptic plane. This plane is defined by the Earth's orbit around the Sun, and it is where the Earth's equator would lie if the axis of rotation were not tilted. The Earth's axis is inclined to the ecliptic plane, and this inclination gives rise to the changing seasons as different parts of the Earth receive varying amounts of sunlight throughout the year.
So, to answer your question, we can say that the Earth is tilted by approximately 23.5 degrees with respect to the ecliptic plane.