Breakdown of kyou wa suupaa de tamago ga tokubai datta node, takusan kaimashita.
Questions & Answers about kyou wa suupaa de tamago ga tokubai datta node, takusan kaimashita.
は marks 今日 as the topic: as for today / today.
So 今日は does not just mean today in a neutral sense; it sets the time frame for the sentence. A very natural literal feel is:
As for today, at the supermarket, eggs were on special, so I bought a lot.
Japanese often marks time expressions with は when they are being treated as the topic or contrastive setting.
で marks the place where something happens.
So スーパーで means at the supermarket or in the supermarket.
Here, the event/state being talked about is that the eggs were on special there. Japanese commonly uses で for the location of an event, action, or situation like this.
- スーパーで買いました = bought them at the supermarket
- スーパーで特売だった = they were on special at the supermarket
