I always think its helpful to think of knitting (and crochet) patterns as being written in code. Its not a hard code to crack and most of the tools for deciphering the instructions are found either in the pattern or easily assessable online or in most knitting books. Throughout the pattern, the stitches used will be usually written in abbreviated form. Hopefully, these are detailed at the start of your pattern, but they may not be. In knitting, these tend to be pretty standard, without the added complication of many UK vs US differences. My go to knitting abbreviation resource is the Craft Yarn Council's list. Its a great place to start if there is something you don't know.
At the start of your pattern, you should be able to see if it is worked in rows or rounds. There is often an indication of whether the side facing you is the right side or the wrong side of your work.
*K2, p2; repeat from * to last 2, k2.
* and [ ] are used to show a stitch pattern is repeated. When you have an astrix, this means you repeat stitch sequence between the * and the ; to a certain end point, such as the end of the round, the end of the row, a stitch marker or, in this case, the last 2 stitches.
[K2, p2] 44 times, k2.
When square brackets are used, it means that the instructions inside should be repeated a set number of times. In the case of the Knit Flat Hat, both of these instructions tell you to do the same thing, they are just different ways of expressing them.
Rows 3-10: As rows 1 and 2.
Repeating rows can be written a number of different ways. In this case, you will work rows 1 and 2 a total of 5 times. This may also be written, "Work rows 1 and 2 a total of 5 times".
Work even until the piece measures 10 cm.
When you see "work even" in a pattern, this means that you should work in the main stitch pattern, without increasing or decreasing. It may be that it tells you to work even for a set number of rows, or until your work is a certain length. If you are measuring, make sure you lay your work on a flat surface and don't stretch it out.
Row 2 (4, 6): K3 (5, 7), P3 (5, 7). (6 (10, 14) sts)
Patterns that come in a range of sizes will have instructions in ( ). Reading from left to right, the numbers relate to the directions for the size from smallest to largest. It may help to go through and highlight the numbers as they relate to the size you are making.
At the end of rows where there is a change to the number of stitches, there should be an indication of what the stitch count should be. This are often written in ( ) or [ ]. These are not an instruction for making stitches, just an aid to tell you how many you should have.
Any other of the basic instructions I have forgotten or any questions? Let me know below!