How to check this company and what they really mean?

They probably see that you are an influencer (blogger?) with the reach they are interested in and want to advertise with you. If you're not that kind of influencer, then it's probably a scam/spam. If you are, send them the services you can offer and take the cash upfront at first.

The shopLC.com website actually exists and looks professional at first glance. They also have a popular Twitter feed https://twitter.com/ShopLCTV and Google results show yet other signs of real activity of such a shop.

See if the mail actually came from the domain of this company or the mentioned Gimmegamma. The latter is probably this: https://gimmegamma.com/ - an advertising agency from the USA. It makes sense that they would write to you on behalf of a client. Perhaps they just want to get SEO links to the client's website.

I can't find anything about the person "Larry WesFranco". You can additionally verify that this message came from the said advertising agency by writing to their general address asking if it is actually their employee.

I remember once I got an invitation from Pantera Capital (a well-known VC fund) that they wanted to invest in us. It was very well prepared, but I noticed minor errors in the message. I wrote directly to Pantera Capital to verify this message. Turns out they didn't send it at all...

Według mojej wiedzy ktoś stara się wyciągnąć od Ciebie dane osobowe.Istnieje jednak możliwość,że to prawdziwa wiadomość.Najlepiej zapytaj o kontakt telefoniczny albo spotkanie w dowolnym miejscu gdyż jesteś zainteresowany współpracą.Pamiętaj nie podawaj żadnych danych.

First of all, do not provide any data and even make an appointment in person

It's always important to be cautious when receiving messages like this from companies you're unfamiliar with. Here are some steps you can take to check this company and see if they're legitimate: Do some research on ShopLC.com - look up their website, reviews, social media accounts, etc. Check if they have a good reputation and if they're a legitimate business. Look up Larry WesFranco and Gimmegamma - see if you can find any information about them and their work. Check if they have any association with Shop LC. Check the email address - make sure it's an official email address and not a fake one. You can do this by looking up the domain name (the part after the @ symbol) and checking if it's associated with the company. Ask for more information - if you're still unsure, you can reply to the email and ask for more details about the Guest Post and their advertising opportunities. Legitimate companies will usually be happy to provide more information. Use common sense - if something seems too good to be true or doesn't make sense, it's probably best to avoid it. Be wary of any requests for personal information or payment. Overall, it's important to stay cautious and do your research before working with any new companies or individuals. By taking these steps, you can help protect yourself and your business from scams or fraudulent activity.