Translation:Our apologies, we do not have any tea.
I'm going to with other people here (minus expletives): the goal here is to learn Finnish, not refine our English skills. It seems therefore that it is much more important to get us to learn the verb pahoila than to be picky about the way one talks to customers in English. So how about we settle for "we apologize"?
Pahoillamme isn't a verb. Paha is the adjective 'bad'. Pahoilla is the adessive plural of paha. So pahoilla would be 'at the bad'. Then -mme is a possessive suffix, meaning 'our'. So pahoillamme is 'at our bad'.
'Olemme pahoillamme' reminds me a bit of "Our bad", and a bit of "We're at fault".
However, I guess there is a verb pahoitella, "to regret/to apologize".