"I worked yesterday."
It's hard to explain because it doesn't translate into English.
です is used as "to be" and it's also used to "do a thing." In this case, 仕事。"(I) do a job."
The past tense form of です is でした。
仕事です。= (I'm) doing a job. 仕事でした。= (I) did a job.
It's not a clean translation, but this is the closest I've related it to in my head. I hope this helps.
Japanese doesn't express ideas in same way as English. So direct translation doesn't work.
Quite often you see what would be the 'verb' in English would be an 'adjective' in Japanese.
for example 'suki'(likeable), in English you would say 'I like it', in Japanese you would say 'suki desu' (it is likeable)
and this kind of thing spans across the whole language. Nouns, adjectives, verbs, collocations etc. Japanese unlike European languages is very distant language to English so a lot of these things might feel very counterintuitive at first.
In this example verb in 'I worked' is replaced with 'there was (deshita) work'
Work might be a noun if it is your place of work. This clearly says worked. Is that not a past verb. Is work not a thing that is done in Japan but rather just something that exists?
I feel that often in these lessons I find the Japanese consider certain English verbs to be nouns. Is there somewhere I can find out which English verbs are Japanese nouns?
Yes, きのうしごとをしました it's "I worked yesterday" or more precisely "I did work yesterday" and きのうしごとでした precisely it's more like a "It was work yesterday" but I think any of them have the same ideia, I also think that きのうしごとがありました could be used. Which would be precisely translated as "There was work yesterday" or "I had work yesterday"
I have a similar issue. It seems only with the female voice over. She doesn't seem to articulate very well and it causes undue confusion. There was a question where she was using Gako in a sentence, but she would take a breath or something right in the middle of the word. So to an untrained ear like mine, it sounded like the "ga" was part of a previous word, and ths "ko" was part of the following word etc. It took me forever to sort rhat one out. It was super frustrating. Haha