If you speak English frequently, you do it often. If you speak English fluently, you do it with a high level of skill.

Here is the answer for the meaning of frequently: 1 frequent /ˈfriːkwənt/ adjective Learner's definition of FREQUENT [more frequent; most frequent] 1 : happening often We made frequent trips to town. a frequent [=common, usual] occurrence This bus makes frequent stops. — opposite infrequent 2 : acting or returning regularly or often She was a frequent visitor to the museum. He is one of our most frequent customers. — opposite infrequent — frequently adverb I see her frequently. This list is updated frequently. 2 frequent /friˈkwɛnt/ verb frequents; frequented; frequenting Learner's definition of FREQUENT [+ object] : to visit or go to (a place) often He began frequenting cheap bars. a neighborhood frequented by tourists a restaurant frequented by local politicians — frequenter noun, plural frequenters [count] a frequenter of cheap bars As you can see it usally means something that happens often. Here is the meaning of fluently: fluent /ˈfluːwənt/ adjective Learner's definition of FLUENT [more fluent; most fluent] 1 a : able to speak a language easily and very well a fluent speaker a fluent speaker of Chinese — often + in He is fluent in Chinese. b ◊ Language that is fluent is language that is spoken easily and very well. She speaks fluent Spanish and a little French. 2 : done in a smooth and easy way We admired their fluent [=fluid] movement across the dance floor. a fluent performance — fluently adverb He speaks seven languages fluently. As you can fluently is used to talk about when a person can speak a language very well or does something in a smooth way.