For tax purposes a Single-Member LLC is not separate from the owner. This is a disregarded entity which means that the LLC is taxed like a sole proprietorship. The owner must report all profits or losses of the LLC by preparing a Schedule C and submit it with the 1040 tax return (Form 1040 or 1040-SR).
An LLC with 2 members or more must file a separate tax return as a partnership. Individual partners are the ones who pay tax on the income based on their share of ownership.