General Emergencies: 112
EU citizens who hold an EHIC (European Health Insurance Card) are entitled to healthcare services just like local residents. These hospitals are more likely to have English-speaking staff: Centro Médico-Milenium Valencia Quironsalud Vithas Hospital Nueve de Octubre My Medica - International Clinic
Travel insurance isn't mandatory, but recommended. Choose a plan that offers coverage for Covid-19 and unexpected quarantine.
*this information is taken from the official CDC website
Being up to date with routine vaccinations is all you need when traveling to Spain.