What does it mean that the Sun`s rotation axis is: RA 286.13° , Dekl: 63.87°?
You can think of the position given in your title as the coordinates of the star that is directly over the Sun's north pole. (Similar to how Polaris is almost directly over the Earth's north pole.) Likewise, the ecliptic plane has a north pole which can be located by right ascension and declination.

7.25° to 7.26° appears to be the correct calculation, based on the following:


North pole of sun: 286.13° RA, 63.87° declination
North pole of ecliptic: 270° RA, 66.5738° declination (per Wikipedia)


$$cos(angle)=sin(dec1)sin(dec2)+cos(dec1)cos(dec2)cos(RA1-RA2)$$
$$cos(angle)=sin(63.87)sin(66.5738)+cos(63.87)cos(66.5738)cos(286.13-270)$$
$$angle=7.26$$