Schengen visas are issued for the purpose of one or more short stays in the Schengen area. The purpose of the entire travel must be something other than work, for example tourism, business, conferences, short courses or visits to family and friends.
A Schengen visa may be granted for a shorter or longer period of time and for one or more entries into the Schengen area depending on the purpose of the travel and the documentation presented by the applicant.
A visa never allows you to work, no matter how short the stay is. If you are going to carry out salaried work in Schengen, you must always apply for a work and residence permit. You must apply for a work permit to each individual country where you are going to work.
A visa never allows you to stay for more than 90 days, no matter what the purpose is. If you are going to stay for more than 90 days, you must apply for a residence permit which allows you to carry out the specific type of activity (for example study or working holiday). You must apply for a residence permit to each individual country where you plan to go.
Please note: Possession of a visa does not confer an automatic right of entry to Schengen. The holder of a visa may be requested to present proof that they fulfil the entry conditions at the external border, as provided for in Article 5 "Entry conditions for third-country nationals" in the Schengen Borders Code.