By signing a human rights treaty a state declares that it has agreed upon the content of the treaty, and intends to work towards its implementation. But only the ensuing ratification leads to a legally binding obligation under international law. Ratification is usually done by the head of state who represents it internationally.
In addition, the term ratification also stands for the domestic procedure that translates treaties under international law into domestic law. In many legal systems, e.g. in Germany, the legislative body has to pass the treaty in question. That is why it can take a considerable amount of time until a signed treaty gets ratified. In other legal systems (e.g. USA, Austria, Netherlands, Spain, France) human rights treaties are directly applicable, i.e. without any implementing legislative act.
Like other treaties under international law, human rights treaties only enter into force once a certain number of states, stipulated in the treaty, has ratified them. Sometimes this happens rather fast: the Convention on the Rights of the Child entered into force within a year; the International Covenant on Economic, Social and Cultural Rights and the International Covenant on Civil and Political Rights, however, were open for ratification for ten years before entering into force.
Deutsche Geschellschaft für Internationale Zusammenarbeit (GIZ) (2013): Promising Practices - On a human rights-based approach in German development cooperation. GIZ, 26 p.
Deutsche Geschellschaft für Internationale Zusammenarbeit (GIZ) (2011): National Human Rights Institutions. GIZ, 10 p.