Your visa should indicate which countries it's valid for. Most commonly, the indication will be Schengen states, or, rather, the equivalent in the language of the issuing country (Lithuanian: Šengeno valstybėse). If your visa is like this, then you may visit other Schengen countries during the visa's period of validity.
The heading for this item appears to be GALIOJA.
Because the visa is a single-entry visa, you must be careful not to leave the Schengen area before you are ready to leave for good. For example, if you want to go to Poland, you may not travel by land through the Kaliningrad Oblast, nor via Belarus. You would either have to cross the Lithuania-Poland border directly, or travel by a direct air or sea connection.