Discrimination is a general term that is defined as preferential or prejudicial treatment of people based on race, gender, age, color, sexual orientation, and several other categories. Racism is is a sub category of discrimination that is a practice of prejudicial treatment of people of other races, groups, communities etc because of feelings of superiority of one’s own race and culture. For example: (1) The boss does not like to hire anyone over the age of 50 since their near retirement age. (The boss is practicing age discrimination.) (2) Black people are only good at sports. (That is a racist statement) Hope that helps!

I wouldn't worry to much. People have typos in their emails all the time. I would continue working on improving your writing skills for any future correspondence with your clients. No one expects perfection.

Both sentences are fine but the second one doesn't sound as natural. In the second sentence, I would replace "a pretext" with "an excuse". But, you can use it as you've written above. Hope that helps!

"Don't get on my bad side" is just a saying that means don't get me angry or do something to make me hate you. Here is a simple example: New Employee: Tell me a little about the boss. Co-Worker: He is a nice guy, but you don't want to get on his bad side. Once you get on the persons bad side you will not be in good standing with them.

Yes, you are correct. It means pay for work or services.

This is American slang that is usually used among friends to mean that he/she is always on point/successful. Here is a simple scenario: (1) John scores 30 points in a basketball game, and a friend comes up to him and says, "Good shooting". He would reply, "that's how I roll". Or if the comment was directed at the whole team, he would reply, "that's how we roll". This can be used in the workplace, athletic competitions, and pretty much anywhere someone did something they are proud about or hold in high esteem. Hope that helps.

It usually refers to when you are unsure of something. For example, you got promoted to a new position and no one told you what you need to do everyday. So if someone asks you what do you do at work. You may answer, I make it up as I go along. Hope that explains it.

You are correct in your understanding of the word "heading". What you are misunderstanding is the latter part of the sentence where it states, "....home for the holidays". Usually in the west (U.S.A., Canada, England) it means that you are visiting your parents or in-laws for the holidays. Therefore, the sentence is saying that you are heading to your parents home. Hope that helps!