Эта оправа с носоупором мне подходит.

Because оправа is a feminine singular noun.

In Russian, words like this must agree with the noun in gender, number, and case:

• этот = masculine
• эта = feminine
• это = neuter
• эти = plural

So:

• эта оправа = this frame

It is in the nominative singular.

That is because оправа is the subject of the sentence — it is the thing that подходит.

So the structure is basically:

• Эта оправа с носоупором = the subject
• мне подходит = suits me / fits me

After с meaning with, Russian normally uses the instrumental case.

The dictionary form is:

• носоупор

In the instrumental singular, it becomes:

• носоупором

So:

• с носоупором = with a nose pad / nose support

This is a very common pattern in Russian:

• с другом = with a friend
• с машиной = with a car
• с носоупором = with a nose support

Because the verb подходить in the sense of to suit / to fit takes the person in the dative case.

So Russian says, literally, something like:

• The frame is suitable to me

That is why you get:

• мне подходит = it suits me / it fits me

not:

• я подходит
• меня подходит

This dative pattern is very common with verbs meaning to suit, please, be necessary, and similar ideas.

Because the subject is эта оправа, which is singular.

The phrase с носоупором is only extra information describing the frame. It does not make the subject plural.

So the verb agrees with оправа:

• эта оправа подходит

If the subject were plural, the verb would also be plural:

• эти оправы подходят

Yes — подходить can mean to approach / come up to, but it also very often means to suit, fit, be appropriate.

Russian uses the same verb for both ideas, and context tells you which meaning is meant.

For example:

• Он подходит к двери. = He approaches the door.
• Эта оправа мне подходит. = This frame suits/fits me.

So in this sentence, подходит clearly means is a good fit / is suitable.

Yes. Russian word order is fairly flexible because the cases show the grammatical roles.

These are all possible:

• Эта оправа с носоупором мне подходит.
• Мне подходит эта оправа с носоупором.
• Эта оправа мне подходит.

The meaning stays basically the same, but the focus changes a little:

• starting with мне emphasizes for me
• starting with эта оправа emphasizes this frame

The version you were given sounds neutral and natural.

No. Оправа means the frame, not the whole pair of glasses.

• оправа = frame
• очки = glasses

So this sentence is specifically talking about the frame being suitable, not necessarily the whole finished pair of glasses.

It is understandable, but it sounds a bit technical or like the kind of word you might see in an optics shop or product description.

It is a compound word, literally something like:

• носо- = nose
• упор = support / rest

So носоупор means a nose support / nose pad on glasses.

In real life, you may also hear related wording depending on context, and sometimes the plural is common when talking about the two pads on a pair of glasses.

Because подходит is present tense and describes a current fact:

• Эта оправа мне подходит. = This frame suits me / fits me.

By contrast, подойдёт is future/perfective:

• Эта оправа мне подойдёт. = This frame will do / will suit me.

If someone is trying on frames right now and judging them, подходит is the natural form.

Usually, no — not if you want to say it suits me.

The word мне tells you who the frame suits. Without it, the sentence becomes incomplete or at least much less specific.

Compare:

• Эта оправа мне подходит. = This frame suits me.
• Эта оправа подходит. = This frame is suitable / works.
  This can be said in the right context, but it is more general and less personal.