What will the edge look like?
It'll look like a sawn face usually looks, based on the wood type (the original cut of the board as well as the species) and the type of saw used.
The second point is more involved than it might at first appear. As this is a rip cut a rip saw will make a much cleaner cut than a crosscut or other saw doing the same cut, but the TPI of the saw is a big factor in either case. Additionally, traditional European saws1 tend to leave a rougher surface than Japanese-style saws made for the same purpose (due to completely different tooth geometry).
So to answer the question again in two ways:
- If done using a European-style rip saw, it'll look sawn and require a fair amount of cleanup.
- If done using a Japanese-style rip saw it'll still look sawn but generally a lot smoother, requiring far less cleanup.
A further question from the Comments:
If I cut along this edge what will I have to do to make the surface look the same as the current surface and is it possible without a mill or some other expensive machinery?
You can do this by sawing and then sanding (working through the grits from coarse to fine). Although I wouldn't recommend this approach2 it will get you to where you need to be if it's the only option open to you. If you go this way I would recommend quickly making up an edge-sander3 which will not only help you sand square to the face of the board it will also help keep the sanded edge straight.
However, do be aware that doing the initial saw cut is probably more challenging than you realise ...it's quite difficult even for a pro to do very straight 2m+ saw cuts, even if using a rip saw and not a modern general-purpose panel saw.
And before you start sawing make sure to do your initial marking up/layout with care, on both faces and both ends of the board, ideally using a marking gauge.
1 Modern 'hardpoint' saws (saws with impulse-hardened teeth) can have modified geometry that is not like those of the textbook teeth in Western woodworking, some with features inspired by Asian saws.
2 I would either do it entirely by planing (using more than one plane by preference, although all the work can in theory be done with a single no. 4) or, saw the bulk of the unneeded portion off and then flatten and smooth the edge with a plane.
3 Various styles of edge-sanding block/jig: