The vast majority of Venezuelans speak Spanish as mother tongue. That has been the case for over 300 years. We have hundreds of thousands of immigrants from Europe outside Spain, from the Middle East and from other regions apart from South America but Spanish is our main language by far. Our Spanish varies from region to region and across social strata and yet one cannot talk about dialects in the same way as one talks about dialects for English, German, Norwegian, Dutch or Italian. People on the coast speak with a more Caribbean accent, people from the Western Venezuelan Andes speak more like Colombians from the Andes, people in Margarita have their way and people in the Llanos or in Guayana speak differently...but just so much. We also use words Spaniards took over from the native American languages and a few taken over from the languages spoken by African slaves. They refer mostly to food and the local nature: arepa comes from Carib/Karina (Carib proper), chinchorro (a sort of hammock) from Chaima (an extinct Carib family), onoto from Tamanaco (another extinct Carib language).
I have always found very revealing to talk to Spaniards who had never been to Spanish America. I discover time after time how some of the expressions I thought were Venezuelan turn out to be Andalusian or Galician or from some other region in Spain...or how some meaning I have was normal in Spain centuries ago, but not now. Nowadays Andalusians and Venezuelans or Galicians and Venezuelans use words people in Madrid do not use, even if they are almost always understood without problem. My dad's mother, an illiterate lady, would use expressions considered "wrong" by traditionalists who follow some prescribing grammar, but as a teenager I started to discover many of those expressions were used by, among others, the Marquis of Santillana, one of the best known Spanish poets of the XV century. People from the "Guaro area", one of the first centres of Spanish colonization in Spanish America- still use verbal forms identical to the ones used by the Spaniards in the XV and start of the XVII centuries: the most traditional voceo. People in Argentine and other American regions also use a form of voceo, but they differ more: "vos amáis" in XV-century Spanish and "Guaro" Spanish, "vos amás" in Argentine Spanish.
About 2% of the population belong to our First Nations. Even though a large part of them speak Spanish, they also speak one (or two) of the some 29 American languages still surviving in Venezuelan territory. We are not talking about dialects, but rather about clearly distinct languages (I won't get here into the language versus dialect issue). Those languages belong to several languages families that are as different as the Romance family to the Germanic one or even as different as the Romance family to Semitic languages. I will talk about some of them on another post.
Above you can see a mind map (in Spanish) representing the main native American languages spoken in Venezuela.
Several of those languages are going to become extinct in the next decades.