Насос лежить біля колеса.

Because біля requires the genitive case. The dictionary form is колесо (wheel), but after біля it changes to колеса, which is the genitive singular form.

So:

• колесо = wheel
• біля колеса = near the wheel

Біля takes the genitive case. It means near, by, or close to.

That is why the noun after it changes form:

• біля колеса = near the wheel
• біля будинку = near the house
• біля машини = near the car

This is a very common pattern to remember.

Лежить is the 3rd person singular form of лежати, meaning to lie, to be lying, or to be in a lying position.

In this sentence, it means the pump is lying there, not standing or hanging. Ukrainian often uses verbs like this more naturally than English does.

So Насос лежить біля колеса is literally something like:

• The pump is lying near the wheel

In natural English, depending on context, you might also translate it as:

• The pump is near the wheel

Ukrainian often uses position verbs such as:

• лежати = lie
• стояти = stand
• висіти = hang

These verbs tell you how something is positioned.

So лежить adds a bit more information than English is. It suggests the pump is resting on a surface, probably horizontally.

If you only want to state location very briefly, you might sometimes hear something shorter in casual or note-like style, but the full sentence with лежить sounds natural and informative.

Ukrainian has no articles. There is no separate word for the or a/an.

So:

• насос can mean a pump or the pump
• колеса here can mean of a wheel or, in context, of the wheel

You understand whether it is a or the from context.

Yes, the form колеса can be ambiguous by itself:

• genitive singular of колесо = of a wheel
• nominative plural = wheels

But in this sentence, there is no real confusion, because біля must be followed by the genitive. So here біля колеса can only mean near the wheel.

Yes. Ukrainian word order is more flexible than English because cases show the grammatical relationships.

For example:

• Насос лежить біля колеса.
• Біля колеса лежить насос.

Both are grammatical. The difference is mainly emphasis:

• Насос лежить біля колеса focuses more naturally on the pump
• Біля колеса лежить насос puts more emphasis on the location

In the present tense, Ukrainian verbs usually show person and number, but not gender.

So лежить means he/she/it lies depending on the subject. It works here with насос simply because насос is 3rd person singular.

Gender becomes visible more clearly in the past tense, for example:

• насос лежав = the pump lay
• книга лежала = the book lay
• яблуко лежало = the apple lay

So in your sentence, лежить is singular, but it does not show masculine specifically.

They are close in meaning, but they are not used in exactly the same way.

• біля = near, by
• поруч із = next to, beside

Also, they take different cases:

• біля колеса → genitive
• поруч із колесом → instrumental

So you could say:

• Насос лежить біля колеса.
• Насос лежить поруч із колесом.

Both are possible, but поруч із can sound a bit more like right next to.

You can, but it sounds more like a label, note, headline, or very compressed speech. In a normal full sentence, Насос лежить біля колеса is better.

Compare:

• Насос лежить біля колеса. = full natural sentence
• Насос біля колеса. = very short, reduced style, like pointing something out or writing a caption

So as a learner, it is safer to use the full version.