Ліхтарик лежить біля ліжка.

Because біля requires the genitive case. The basic dictionary form is ліжко meaning bed, but after біля it changes to ліжка.

So:

• ліжко = nominative singular
• біля ліжка = near the bed

This is a very common pattern in Ukrainian.

Біля takes the genitive.

That means the noun after it must appear in the genitive form:

• біля ліжка = near the bed
• біля столу = near the table
• біля вікна = near the window

If you learn біля + genitive as a set pattern, it becomes much easier.

Good question, because ліжка can also be the nominative plural form meaning beds.

Here, the preposition біля tells you what is happening. Since біля requires the genitive, ліжка here must be understood as genitive singular: of the bed / near the bed.

So the grammar around the word tells you its function.

Лежить is the 3rd person singular present form of лежати, which means to lie or to be lying.

So лежить means:

• lies
• is lying

In this sentence, it describes the flashlight as being in a lying position near the bed.

Ukrainian often prefers a position verb when talking about where something is physically located.

Common ones are:

• лежати / лежить = to lie
• стояти / стоїть = to stand
• висіти / висить = to hang

So instead of a plain is, Ukrainian often tells you how the object is positioned.

Compare:

• Ліхтарик біля ліжка = The flashlight is by the bed
• Ліхтарик лежить біля ліжка = The flashlight is lying by the bed

The second version is more specific.

Grammatically, є is the present-tense form of to be, but in ordinary Ukrainian it is usually not used in simple present-tense sentences like this.

So:

• Ліхтарик біля ліжка = natural
• Ліхтарик лежить біля ліжка = natural
• Ліхтарик є біля ліжка = usually unnatural in everyday speech

In short, Ukrainian normally either omits the present to be or uses a more specific verb like лежить.

That depends on how the object is positioned.

• лежить = lying, resting flat or horizontally
• стоїть = standing upright
• висить = hanging

A flashlight on its side near the bed would naturally лежить.
A bottle or lamp standing upright would more naturally стоїть.

So the choice reflects the physical orientation of the object.

Yes, ліхтарик is a diminutive form related to ліхтар.

Often, diminutives in Ukrainian can suggest:

• small size
• affection
• informality

But in real usage, ліхтарик is also a very normal everyday word for flashlight. It does not always need to sound especially cute or emotional in context.

No, Ukrainian word order is fairly flexible.

Ліхтарик лежить біля ліжка is a neutral, natural order. But other orders are possible, for example:

• Біля ліжка лежить ліхтарик
• Лежить ліхтарик біля ліжка

These can shift the emphasis:

• starting with ліхтарик puts the flashlight first as the topic
• starting with біля ліжка emphasizes the location first

So the basic meaning stays similar, but the focus can change.

Because Ukrainian has no articles.

So ліхтарик can mean:

• a flashlight
• the flashlight

and ліжка can mean:

• a bed
• the bed

The exact meaning depends on context. English needs articles, but Ukrainian does not.

Yes. Ukrainian has several common options.

For example:

• біля ліжка = near the bed
• коло ліжка = near the bed
• поруч із ліжком = next to / beside the bed

Notice the case change:

• біля
  • genitive → ліжка
• коло
  • genitive → ліжка
• поруч із
  • instrumental → ліжком

So the meaning is similar, but the preposition determines the case.