There should be a lot more foot traffic because the store opened for the first time only two days ago.
For a shop that only opened two days ago, there should be a lot more customers.
This is really slow for a store that just opened two days ago.
英訳① There should be ...で「…があるはずだ」という文です。
foot traffic は「歩行者交通」、つまり「客の出足」ということ。
「開店してまだ２日」は、open for the first time only tow days ago（２日前に初めてオープンしたばかり）と表現しています。
英訳② 「２日前に開店したばかりの店なら、もっと客が多くなければおかしい」という文です。
英訳③ ビジネスなどが slow といった場合は、「不振な、人気のない」という意味です。
他にこんな言い方も！
- Normally there would be a lot more foot traffic for a new store that's only been open for two days.
- There should be a lot more customers for a store that just opened two days ago.
With the new opening two days ago, there should be more customers.
First, mentioning the amount of time between of the opening and the current state gives a sense of urgency or confusion depending on your desire. Stressing that there is a lack of business lets those that you are speaking to know what is wrong.
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