Here's the lowdown of some of the abbreviations you might see on patterns, so you aren't there thinking OMG WTF!
They're just for speed and to save space from being written out fully.
CF - Centre Front- is exactly what is sounds like, the very centre of the front of the garment. Usually the CF will be straight and the same as the grainline
CB - Centre Back - the very centre of the back of the garment. This can either be straight or have shaping
RSU - Right side up - this is a cutting instruction to make sure when you're cutting, the right side of the fabric is the same way up as the pattern
WSU - Wrong side up - again this is a cutting instruction, but this time the fabric should be the opposite way up from the pattern
SS - Side Seam
RHSAW - Right Hand Side As Worn - this is to make it clear with left and rights - most patterns will have you left and right labelled as if you were wearing the garment
LHSAW - Left Hand Side As Worn
SA - Seam allowance
OL - Overlock
GL - Grainline
RST - Right sides together - when sewing you usually stitch right sides of the fabric together so when you press your seams and turn the garment through you've got the right side of the fabric on the outer.
WST - Wrong sides together - wrong sides together means the seam allowance will be on the outside - this is mostly used as a style feature or when doing a french seam where the first stage is to stitch wrong sides together
WL - Waistline
BLK fuse - Block fuse - fuse the fabric before cutting out all the pieces that need fusing so you don't need to attach the fusing separately to each piece- this is faster and more accurate
ZZ - Zigzag stitch