HELP - pattern terminology

[jen123]

Hi, I am just starting to knit and have chosen to to a sirdar all in one baby suit with snuggly snowflake chunky wool.

I understand basic knitting stitches but the pattern reads:

working in st-st proceed as follows:
work 4 rows inc 1 st at the end of every row.
Place markers at the end of last row.
13 sts.
Work 14 rows more without shaping.

I understand the st-st and working the next 4 rows, but i am totally lost for what to do when i get to the line about the markers, also it says 'without shaping' but i didnt think i had done any shaping?

PLEASE HELP!!!