パパは土日は会社お休みだよって英語でなんて言うの？

会社お休みは仕事休みで off work って表現を使えます。

土日は は週末のことを指すので in the weekend でも使えますが
子供に分かりやすいように 土曜日と日曜日は と言いたい場合は
on Saturday and Sunday と言った方が良いでしょう。

If you would like to use British English then you would say 'at the weekend' and 'at weekends'
If you would like to use American English then you would say 'on the weekend' and 'on weekends'
-My sentences above are British English.
Other vocabulary for 'daddy' includes, 'dad' - used by older children and 'father' which is more formal.

Any of these phrases will let your child know that you do not have to work on weekends. You could also say something like ‘Daddy isn’t working (on) weekends’. If you used to work on weekends, you could add ‘anymore’: for example, ‘Daddy doesn’t work weekends anymore’.

The first phrase has a slight air of celebration about it, by using the words "good news", as this is likely to make the listener happy.
The second phrase confirms that, "from now on", which means all future weekends, , Daddy does not have to work and will be around.
The third phrase is a direct statement, or exclamation, and uses a rhetorical question (Guess what) to start the sentence, and conveys that the person is glad they are not needed to work any further weekends.

The days per week and the hours per day that an employee is expected to be at their workplace is referred to as a work schedule. This especially true for workers who do shift work. Nonetheless, if your dad isn't expected to work on weekends, we can say he's not scheduled to work.

If you would like to tell your child that their father does not need to work on weekends, you can say something like "Your dad does not need to work on the weekends." or "Daddy doe not need to work on Saturday and Sunday's.". This is an easy way to say this to your child.

1. Your dad doesn't have to go into work over weekends.
   The weekend is comprised of both a Saturday and a Sunday
   and is usually your free time when you can enjoy personal
   activities with friends and family. Some people are in the
   unfortunate position that they have to work some weekends
   out of every month. The sentence: "Your dad doesn't have to
   go into work over weekends." means that he is not required
   to go into the workplace over weekends.
   However, if you say: "Your dad doesn't have to go in over
   THE weekend", it means that he often does work over
   weekends, but that he will not be doing so this forthcoming
   weekend.

2. Your dad only works from Monday to Friday.
   This is self-explanatory. The dad's job does
   not require him to put in any weekend work.

'Daddy does not have work on the weekend.' is what you can tell your son/daughter when trying to explain to them, and it simply means that dad does not have to go in to work on the weekend, the weekend is his off time and relaxation time.

When you are a parent, you have two jobs. You have your regular job where you go every day except your days off, and then you have to be a parent which is another job in itself. It can be hard to balance the two as you may need to work longer hours and when you come home you may have no time to spend with your child.

These two sentences explain clearly that the father doesn't have to work at the weekend. As the child gets older he or she becomes aware of how things work and will wonder where the father goes every day. Maybe she or he might become upset because the father isn't around. The mother can confirm to the child with these informal sentences.

It is natural in modern-day English to omit "on the" and just write "weekends". This is a shortened grammatical form that you may hear often.
If someone is "free", it means they have free time, which connotes not having any work to do!
If the father has a job where he goes to an office, for example, you can say that he "stays home" to imply that he doesn't have work those days!

Explaining the days of the week to the child is a great way to get them to understand the difference in the days. Also, telling them what days are weekend days can be helpful as well.