It is not a legally binding step, but is an indication that the country intends to undertake a careful examination of the treaty in good faith to determine its position towards it. While signing the Convention does not in any way commit the country to proceed to ratification, it does create an obligation to refrain from acts that would defeat the objectives of the Convention, or to take measures to undermine it. Articles 47 and 48 of the Convention state that a country can become a State Party to it either by ratification or accession. Both of these acts signify an agreement to be legally bound by the terms of the Convention. The distinction refers to two different procedures to becoming a State Party and is essentially irrelevant.
Accession has exactly the same effects as ratification.
Most commonly, a country in favour of a convention signs shortly after it has been adopted and follows up with ratification when all procedures required by domestic law have been fulfilled. Countries that have not signed can become States Parties through accession to the Convention. Both ratification and accession involve two steps. The date of receipt of the document is then registered as the date of ratification or accession for the country in question. The Convention becomes legally binding in the country 30 days after the instrument of ratification or accession has been received.