这个句子应该是正确的.
Learn English well 这句,主语明显省略掉了,应该是[If you] learn English well,如果你把英语学好,省略掉了主语you.然后这个句子应该是主谓宾结构,you是省略掉的主语,learn是谓语,English是宾语,well是宾语补足语,来补充完善宾语.
you will have a good future这句是主系表结构,you做主语,have是系动词,a good future是表语,will是情态动词在这里只起到修饰have的作用.
"Learn English well,you will have a good future."不含从句.