Q: putting them on the key holder which happens to look like a large key とはどういう意味ですか?
A: Happens to = ironically, funnily coincidentally.
When ‘happens to’ is added to a sentence it shows that there is a joke or something funny or coincidental.
Key holder in a key shape is funny.
Hope that helps~
Q: holder とはどういう意味ですか?
A: It has several meanings. One is something that holds something or in which something is placed - e.g. a phone holder is where you put your phone when not in use. It can also mean the person or team that is the current champion of something e.g. Barcelona are the current holders of the Spanish Super Cup.
Q: pan holders とはどういう意味ですか?
A: https://www.google.com/imgres?imgurl=https%3A%2F%2Fimages-na.ssl-images-amazon.com%2Fimages%2FI%2F81iqHH0wyJL._SX466_.jpg&imgrefurl=https%3A%2F%2Fwww.amazon.com%2FHanging-Kitchen-Ceiling-Cookware-Storage%2Fdp%2FB00PDMFBAO&docid=_pngik9OL0B_HM&tbnid=00IlnGK9rMQ5pM%3A&vet=1&source=sh%2Fx%2Fim


Q: holder を使った例文を教えて下さい。
A: i use a pencil holder to hold up all my pens and pencils.


Q: holder of the letter と bearer of the letter はどう違いますか?
A: The "holder" of something is the one who's responsibility is to keep it safe.

The "bearer" of something is the one who's responsibility is to carry something.

So, in case of a holder, even if the thing is yours and he is holding it for you, it is not his responsibility to deliver it to you.

In case of the bearer, if the thing is yours, then he should carry it and deliver it to you.

"Holder of the keys", he might lock them up in safe.
"The bearer of the keys", he carries them with him on his person.
Q: a commutation‐ticket holder と a season‐ticket holder はどう違いますか?
A: The person who owns the ticket. "Holder" is often used to mean "a person who has something", like shareholder (a person who owns shares in a business) or record-holder (someone who has a world record).


Q: holder は 英語 (アメリカ) で何と言いますか?


Q: I put a key holder on my bag. It swings when I walk. この表現は自然ですか?
A: × I put a key holder on my bag.
✓ I put a keychain on my bag.

キーホルダー = keychain (和製英語かもしれません)
Q: A holder of Master's degree has passed the advanced course of specialization – one or two years and can be engaged in practical activities in the chosen specialty. この表現は自然ですか?
A: QAの全文をご確認ください