"Those women were very good."
Translation:वे औरतें बहुत अच्छी थीं।
It says वे -'those' (pronounced 've').
It is the plural form of वह - 'that' which is usually pronounced 'vo' though it is written as 'vaha'. These kinds of unphonetic pronunciations are common in words containing the letter 'ह'.
Similarly, 'this' is यह which is usually pronounced 'ye' though it is written as 'yaha'. The plural form, 'these' is unambiguously ये (ye).
'Here' is 'यहाँ' (yahā̃) where the vowel at the end has to be nasalised.
था /थी is the past tense form of होना ('to be'). In this sentence, it is the main verb and is in the simple past tense.
However, like other forms of होना, था /थी is also used as an auxiliary verb that marks the tense of another verb.
It is not used to indicate the simple past tense of other verbs. Eg: मैं गया - 'I went', मैंने खेला - 'I played'
It is used to mark the other past tenses:
1. Past imperfect - मैं जाता था -'I used to go', मैं खेलता था - 'I used to play'
2. Past progressive - मैं जा रहा था-'I was going', मैं खेल रहा था - 'I was playing'
3. Past perfect- मैं गया था - 'I had gone', मैंने खेला था - 'I had played'
'Those women used to be very good' would be something like 'वे औरतें बहुत अच्छी होती थीं' where होती functions as the main verb and थीं as the tense auxiliary. (Note: This sentence actually sounds somewhat unnatural when the subject is a person and something like वे औरतें बहुत अच्छी हुआ करती थीं is used instead).
For transitive verbs (verbs which can take direct objects), the subject needs to be followed by the postposition ने in the simple past tense (and perfect tenses). Also, the verb agrees with the gender/number of its objects in these tenses and not the subject as is the case for intransitive verbs.
Eg: खाना (to eat) is a transitive verb
नेहा ने आम खाया - 'Neha ate a mango' (Note that खाया is masculine because आम is masculine)
आपने रोटी खाई - 'You ate a roti' ( खाई is feminine because रोटी is feminine)
The Past 2 lesson includes sentences in the simple past and the present perfect. I don't think the current version of the tree covers the past perfect but it is very similar to the present perfect except that you switch the है/हैं/हो/हूँ with था/थे/थी/थीं.
राज ने एक किताब लिखी है। - Raj has written a book
राज ने एक किताब लिखी थी। - Raj had written a book
Do you mean the dot in ' थीं '? It is used when the subject is feminine AND plural (and indicates nasalisation of the vowel in the word) . 'थी' without the dot is used when the subject is feminine and singular. For instance, 'That woman was very good' would be वह औरत अच्छी थी।